Sync data is not your database(s), so keep that logically separated in your mind.
No, it wasn’t a good idea to set up multiple sync methods and try them all at once. However, it’s unlikely you did any damage.
You need to disable and delete all the sync locations on all devices but one, likely a Mac.
Go into DEVONthink’s Settings > Sync, Control-click a sync location you’ve used, and choose Clean Location. This will remove any sync data that may be stored there. You can optionally, press the minus (-) button to remove the location.
Repeat with other locations you tried to use.
If you followed correctly, you should be as close to square one as possible without reinstalling (which I do not recommend in this case).
Now, I recommend you check out this forum post…