Reproduction steps:
1) Open attached project with Unity 5.3
--- Could be a different version, but there has to be a newer release that would require a reimport of assets
2) Close the editor when it has finished importing assets
3) Duplicate the project
4) Make sure that Cache server is running
5) Make sure that your editor is connected to the cache server
6) Open original project in 5.4
--- Observer that textures are reimported, it's expected
7) Open duplicate project in 5.4
--- Observer that textures are reimported, that shouldn't happen

You can find video of reproduction steps attached