Hi Mixvibes!
I'am currently experiencing similar errors. I'am using FolderSync too sync my music files with a Google Drive folder. After the sync the media library will be rescanned and all new mp3's are added to the Android database. In Google Music all titles are displayed just once. But after the first sync with FolderSync all titles have a duplicate title as well:
I could easily delete the media database and rescan it and I would also have a clean database in Mixvibes... until the next sync with Google Drive which duplicates all items. Also I need to reanalyse all files after db reset which takes hours.
I have an Nexus 7 with Mixvibes Free 1.41 (Full Value Package) and I noticed it since my purchase of v1.3
Regards, Darius