Deleting Indexed items

But I don’t have any imported items in DT, everything is indexed.

I am wondering if the reason there were some imported items in my trash is related to another small mystery that has only happened very recently:

I found identical copies of a few Numbers spreadsheets I had edited very recently, File names were “My name copy” and modification dates were the same to the second. I deleted these but now wonder if they were the imported ones causing the message in my OP.

Any suggestions how/why these copies might have started appearing very recently when I have been modifying these same files every few days for a year or two?

Next time it happens I will check if the copy also appears in the Dropbox folder.

I assume there is a way to search a database for numbers of imported and indexed files? I would like to check if any other imported files remain.