Skeletal mesh reimport via legacy import creates duplicate Mesh sockets

Reimporting a Skeletal Mesh via legacy import duplicates mesh sockets.
The issue does not reproduce when using the Interchange pipeline.

1. Set Interchange.FeatureFlags.Import.FBX=False.
2. Use Asset Actions to export the following asset as an FBX file:
   /Engine/Tutorial/SubEditors/TutorialAssets/Character/TutorialTPP
3. Import the exported FBX file.
4. Open the Skeletal Mesh and add a new Mesh Socket.
5. Reimport the Skeletal Mesh.

Result
The Mesh Socket is duplicated after reimport.