Update Publishing.props (#4271)

eng/Publishing.props

@@ -4,6 +4,8 @@
     <ProducesDotNetReleaseShippingAssets>true</ProducesDotNetReleaseShippingAssets>
     <!-- This avoids creating VS.*.symbols.nupkg packages that are identical to the original package. -->
     <AutoGenerateSymbolPackages>false</AutoGenerateSymbolPackages>
+    <!-- Set PlatformName to TargetArchitecture to create unique build manifest files. -->
+    <PlatformName>$(TargetArchitecture)</PlatformName>
   </PropertyGroup>
 
   <Target Name="AddRelativeBlobPathToArtifacts"