VRChat SDK includes folders originally from Standard Assets in different file paths. So, for example, importing VRCSDK package modifies some Standard Assets folder content. Although importing dialog window warns about that, I think this is unexpected behavior for users.

Attached first image is a example of importing VRCSDK dialog. In this case, I import Standard Assets first, and try to import VRCSDK next. You can see VRCSDK files will go Standard Assets folder ("Standard Assets/Prototyping/Materials" etc.)

Note: 1) Files with "NEW" icon are only in VRCSDK. 2) Files with cycling arrow icon are common files and have differences. 3) Other Files (without checkbox) are common files and have identical content. Some common files have different file name. For example, "prototype_steps_4x2x2.FBX" in VRCSDK has identical ID (guid) "StepsPrototype04x02x02.fbx" in Standard Assets. ("Assets/VRCSDK/Examples/Sample Assets/Prototyping/Models/prototype_steps_4x2x2.FBX" and "Assets/Standard Assets/Prototyping/Models/StepsPrototype04x02x02.fbx")

In attached second image case, I change the order. VRCSDK is first and Standard Assets next. In this case some Standard Assets files will go to VRCSDK folder. (Files with gray out name string are only in VRCSDK.)

Currently, content differences seem not be destructive with exception cases in which user modified Standard Asset files.

Troubling cases that I can imagine are shared project among some persons. They might confuse because file names (and path) could be different depending importing order. (Workaround is making importing order rule among members.)

SDK users already use these files. So I think it's difficult to fix anymore. Instead I propose making a note as a known bug.