While those double writes don't cause immediate build issues, they kill msbuild's incremental build feature which results in a very poor inner-loop experience.

As the list only contains Microsoft.Extensions.* libraries, this code block could be faulty:

Unrelated but we should move that code into intellisense.targets as well.

@carlossanlop please take a look. You can observe the double writes in a binlog. The MSBuild Structure Build Log Viewer shows them as a node.