diff --git a/op-supervisor/supervisor/backend/db/fromda/update_test.go b/op-supervisor/supervisor/backend/db/fromda/update_test.go
index d73ddbb6ef39..9d1158463bbc 100644
--- a/op-supervisor/supervisor/backend/db/fromda/update_test.go
+++ b/op-supervisor/supervisor/backend/db/fromda/update_test.go
@@ -1,6 +1,7 @@
 package fromda
 
 import (
+	"github.com/ethereum/go-ethereum/crypto"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -24,6 +25,8 @@ func TestBadUpdates(t *testing.T) {
 	cSource := mockL1(3)
 	cDerived := mockL2(203)
 	dSource := mockL1(4)
+	dAltSource := mockL1(4)
+	dAltSource.Hash = crypto.Keccak256Hash([]byte("bad alternative block d"))
 	dDerived := mockL2(204)
 	eSource := mockL1(5)
 	eDerived := mockL2(205)
@@ -39,34 +42,110 @@ func TestBadUpdates(t *testing.T) {
 
 	testCases := []testCase{
 		{
-			name: "add on old derivedFrom",
+			name: "add on old derivedFrom before DB start",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(bSource, aSource.Hash), toRef(dDerived, cDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(bSource, aSource.Hash), // b is before c
+					toRef(dDerived, cDerived.Hash)), types.ErrSkipped)
 			},
 			assertFn: noChange,
 		},
 		{
-			name: "repeat parent derivedFrom",
+			name: "repeat second latest",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(cSource, bSource.Hash), toRef(dDerived, cDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(cSource, bSource.Hash),
+					toRef(cDerived, bDerived.Hash),
+				), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
+		{
+			name: "repeat latest",
+			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				require.NoError(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(dDerived, cDerived.Hash),
+				))
+			},
+			assertFn: noChange,
+		},
+		{
+			name: "repeat latest derived, old derivedFrom",
+			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				require.NoError(t, db.AddDerived(
+					toRef(eSource, dSource.Hash),   // new L1 block
+					toRef(dDerived, cDerived.Hash), // same L2 block
+				))
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),   // d is old, but was canonically linked like this before
+					toRef(dDerived, cDerived.Hash), // same L2 block
+				), types.ErrIneffective)
+			},
+			assertFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				pair, err := db.Last()
+				require.NoError(t, err)
+				require.Equal(t, eSource, pair.Source)
+				require.Equal(t, dDerived, pair.Derived)
+			},
+		},
+		{
+			name: "repeat latest derived, conflicting old derivedFrom",
+			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				require.NoError(t, db.AddDerived(
+					toRef(eSource, dSource.Hash),   // new L1 block
+					toRef(dDerived, cDerived.Hash), // same L2 block
+				))
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dAltSource, cSource.Hash), // conflicting old block
+					toRef(dDerived, cDerived.Hash),  // same L2 block
+				), types.ErrConflict)
+			},
+			assertFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				pair, err := db.Last()
+				require.NoError(t, err)
+				require.Equal(t, eSource, pair.Source)
+				require.Equal(t, dDerived, pair.Derived)
+			},
+		},
+		{
+			name: "new derived, old derivedFrom",
+			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				require.NoError(t, db.AddDerived(
+					toRef(eSource, dSource.Hash),   // new L1 block
+					toRef(dDerived, cDerived.Hash), // same L2 block
+				))
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),   // old L1 block
+					toRef(eDerived, dDerived.Hash), // new L2 block
+				), types.ErrOutOfOrder)
+			},
+			assertFn: func(t *testing.T, db *DB, m *stubMetrics) {
+				pair, err := db.Last()
+				require.NoError(t, err)
+				require.Equal(t, eSource, pair.Source)
+				require.Equal(t, dDerived, pair.Derived)
+			},
+		},
 		{
 			name: "add on conflicting derivedFrom, same height. And new derived value",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(types.BlockSeal{
-					Hash:      common.Hash{0xba, 0xd},
-					Number:    dSource.Number,
-					Timestamp: dSource.Timestamp,
-				}, cSource.Hash), toRef(eDerived, dDerived.Hash)), types.ErrConflict)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(types.BlockSeal{
+						Hash:      common.Hash{0xba, 0xd},
+						Number:    dSource.Number,
+						Timestamp: dSource.Timestamp,
+					}, cSource.Hash),
+					toRef(eDerived, dDerived.Hash)), types.ErrConflict)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "CrossSource with conflicting parent root, same L1 height, new L2: accepted, L1 parent-hash is used only on L1 increments.",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.NoError(t, db.AddDerived(toRef(dSource, common.Hash{0x42}), toRef(eDerived, dDerived.Hash)), types.ErrConflict)
+				require.NoError(t, db.AddDerived(
+					toRef(dSource, common.Hash{0x42}),
+					toRef(eDerived, dDerived.Hash)), types.ErrConflict)
 			},
 			assertFn: func(t *testing.T, db *DB, m *stubMetrics) {
 				pair, err := db.Last()
@@ -78,46 +157,59 @@ func TestBadUpdates(t *testing.T) {
 		{
 			name: "Conflicting derivedFrom parent root, new L1 height, same L2",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(eSource, common.Hash{0x42}), toRef(dDerived, cDerived.Hash)), types.ErrConflict)
+				require.ErrorIs(t,
+					db.AddDerived(
+						toRef(eSource, common.Hash{0x42}),
+						toRef(dDerived, cDerived.Hash)), types.ErrConflict)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on too new derivedFrom (even if parent-hash looks correct)",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(fSource, dSource.Hash), toRef(eDerived, dDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t,
+					db.AddDerived(toRef(fSource, dSource.Hash),
+						toRef(eDerived, dDerived.Hash)), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on old derivedFrom (even if parent-hash looks correct)",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(cSource, bSource.Hash), toRef(cDerived, dDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(cSource, bSource.Hash),
+					toRef(cDerived, dDerived.Hash)), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on even older derivedFrom",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(bSource, aSource.Hash), toRef(dDerived, cDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(bSource, aSource.Hash),
+					toRef(dDerived, cDerived.Hash)), types.ErrSkipped)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on conflicting derived, same L2 height, new L1 block",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(eSource, dSource.Hash), toRef(types.BlockSeal{
-					Hash:      common.Hash{0x42},
-					Number:    dDerived.Number,
-					Timestamp: dDerived.Timestamp,
-				}, cDerived.Hash)), types.ErrConflict)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(eSource, dSource.Hash),
+					toRef(types.BlockSeal{
+						Hash:      common.Hash{0x42},
+						Number:    dDerived.Number,
+						Timestamp: dDerived.Timestamp,
+					}, cDerived.Hash)), types.ErrConflict)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add derived with conflicting parent hash, new L1 height, same L2 height: accepted, L2 parent-hash is only checked on L2 increments.",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.NoError(t, db.AddDerived(toRef(eSource, dSource.Hash), toRef(dDerived, common.Hash{0x42})), types.ErrConflict)
+				require.NoError(t, db.AddDerived(
+					toRef(eSource, dSource.Hash),
+					toRef(dDerived, common.Hash{0x42})), types.ErrConflict)
 			},
 			assertFn: func(t *testing.T, db *DB, m *stubMetrics) {
 				pair, err := db.Last()
@@ -129,28 +221,36 @@ func TestBadUpdates(t *testing.T) {
 		{
 			name: "add derived with conflicting parent hash, same L1 height, new L2 height",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(eDerived, common.Hash{0x42})), types.ErrConflict)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(eDerived, common.Hash{0x42})), types.ErrConflict)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on too new derived (even if parent-hash looks correct)",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(fDerived, dDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(fDerived, dDerived.Hash)), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on old derived (even if parent-hash looks correct)",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(cDerived, bDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(cDerived, bDerived.Hash)), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
 		{
 			name: "add on even older derived",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
-				require.ErrorIs(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(bDerived, aDerived.Hash)), types.ErrOutOfOrder)
+				require.ErrorIs(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(bDerived, aDerived.Hash)), types.ErrOutOfOrder)
 			},
 			assertFn: noChange,
 		},
@@ -158,7 +258,9 @@ func TestBadUpdates(t *testing.T) {
 			name: "repeat self, silent no-op",
 			setupFn: func(t *testing.T, db *DB, m *stubMetrics) {
 				pre := m.DBDerivedEntryCount
-				require.NoError(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(dDerived, cDerived.Hash)), types.ErrOutOfOrder)
+				require.NoError(t, db.AddDerived(
+					toRef(dSource, cSource.Hash),
+					toRef(dDerived, cDerived.Hash)), types.ErrOutOfOrder)
 				require.Equal(t, pre, m.DBDerivedEntryCount)
 			},
 			assertFn: noChange,
@@ -170,7 +272,9 @@ func TestBadUpdates(t *testing.T) {
 			runDBTest(t,
 				func(t *testing.T, db *DB, m *stubMetrics) {
 					// Good first entry
-					require.NoError(t, db.AddDerived(toRef(dSource, cSource.Hash), toRef(dDerived, cDerived.Hash)))
+					require.NoError(t, db.AddDerived(
+						toRef(dSource, cSource.Hash),
+						toRef(dDerived, cDerived.Hash)))
 					// apply the test-case setup
 					tc.setupFn(t, db, m)
 				},