Google Music's new scan-and-match feature makes uploading your music much faster, but some users have been noticing incorrect matches?particularly getting clean versions of a song in place of explicit versions, and vice-versa. Here's how to fix that.
If you're having problems with a song Google Music has matched, just find it in your library, click the arrow to the right of its title, and choose "Fix Incorrect Match" from the dropdown. It should then upload the version you have to ensure its the correct song. Unfortunately, you can't do this for entire albums, but if you just have a few incorrect songs it should be an easy fix.
Tip: How to Fix Poorly Matched Songs in Google Music, Explicit Ones Included | Droid Life