Only save package properties for track 2 packages (#6544)

* Only save package properties for track 2 packages (prevents overwrites of track 2 package info by track 1 packages)

* Only overwrite if the package is track 2

eng/common/scripts/Save-Package-Properties.ps1

@@ -10,6 +10,10 @@ an artifact name property is available in the package properties.
 Can optionally add a dev version property which can be used logic for daily 
 builds.
 
+In cases of collisions where track 2 packages (IsNewSdk = true) have the same 
+filename as track 1 packages (e.g. same artifact name or package name), the
+track 2 package properties will be written.
+
 .PARAMETER serviceDirectory
 Service directory in which to search for packages
 
@@ -87,6 +91,7 @@ function GetRelativePath($path) {
   return $relativePath
 }
 
+$exportedPaths = @{}
 $allPackageProperties = Get-AllPkgProperties $serviceDirectory
 if ($allPackageProperties)
 {
@@ -114,6 +119,15 @@ if ($allPackageProperties)
           Write-Host "Creating directory $($outDir) for json property file"
           New-Item -ItemType Directory -Path $outDir
         }
+
+        # If package properties for a track 2 (IsNewSdk = true) package has
+        # already been written, skip writing to that same path.
+        if ($exportedPaths.ContainsKey($outputPath) -and $exportedPaths[$outputPath].IsNewSdk -eq $true) {
+          Write-Host "Track 2 package info with file name $($outputPath) already exported. Skipping export."
+          continue
+        }
+        $exportedPaths[$outputPath] = $pkg
+
         SetOutput $outputPath $pkg
     }