If DEVONthink To Go - or DEVONthink - shows two databases with the same name, they are not the same database and will not sync together. Creating a new database with the same name will never work as it’s a new and separate database, regardless what the name is. Only true copies of a database can sync.
True copies are archieved:
- Importing a database from a sync location to the local device, Mac or mobile
- Copying a database - the .dtBase2 file - to a Mac manually.
PS: This is all covered in the Help > Documentation > In & Out > Sync section.
PPS: Perhaps this update to my Sync Types Explained post is helpful…