RM 11 - what is a .DUP file?

What is a file that ends with .DUP? What is it for, and can I safely delete it?

I believe they are intermediate results files and are used temporarily during Automatic Merge operations to store interim database-related info.

EDIT: They are small SQLite database files temporarily attached to RM’s main database during merge-related operations involving the DupTable*.*

It’s a temporary file used during Duplicate Search/Merge operations. RM normally deletes it when it is done with the Duplicate Search/Merge, but sometimes it forgets to do the delete. It is safe to delete.