It has happened several times that a Devonthink database with a size of several GB has copied itself into the inbox on my DT and it was then synchronised with the existing database. After subsequently deleting the duplicate database and synchronising again, everything was fine again.
Is there an explanation for this unintentional duplication?
A smart rule?
No, it only happens relatively rarely and is not reproducible for me.
A complete database (extension .dtBase2 or .dtSparse)? Importing/indexing actually skips such files.
Yes, it is the complete database. But I didn’t pay attention to the extension.
How do you usually open this database?
Hold the Option key and choose Help > Report bug to start a support ticket.
I normally open the database xyz.dtSparse with a keyboard shortcut of the programme Keyboard Maestro. This always works without any problems. Could it be that another shortcut, which I don’t know (any more), activates the import of the same database into the Inbox? I have not been able to find anything in this regard.
No. And as mentioned previously, you can’t import a database into another one.
After subsequently deleting the duplicate database and synchronising again,
You can’t synchronize a database you’ve deleted. You need to import it. To where are you importing the database?
Thank you, Jim, for your answer. I will now try to describe the process in a more understandable way.
I see that in the Inbox of Devonthink the same database with the same name is imported.
At the same time, DT starts uploading the files from the DT-Inbox to the Dropbox sigstore.
I delete the duplicate database in the DT-Inbox and immediately empty the recycle bin with the deleted file. But:
DT still continues to upload the files to the Dropbox sigstore! Only when all the files have been uploaded does DT stop - and everything seems to be fine. It looks like the synchronisation took place and the synchronisation deleted the duplicate files.There are no duplicate files in the Dropbox sigstore, as would have been expected.
Conclusion:
Maybe next time I shouldn’t delete the duplicate database, but see what happens during synchronisation on my other Macs. If the file is twice as big, are there duplicates? So far I don’t know, because I don’t want to duplicate my database … 
Please start a support ticket as described above. Also include screen captures of what you’re seeing.
Thank you, I have just emailed.
I cannot send a screenshot with the error, as the error is currently fixed and the database is working normally.