Hidden .dtBase2 files

Cleaning up a directory where I store some databases, I noticed four hidden files with names similar to a database I use regularly. Say that my database is named ABC-data.dtBase 2, I have three hidden files named

Each of these is roughly a year old, and they have datestamps roughly a week apart. They are about half the size of the real ABC-data.dtBase2 database. Since my real database is behaving just fine, I’m assuming I can get rid of these files. But, having never seen this before I’m checking whether anyone else has noticed this type of thing and what process might have created them.

When un-hidden, these are valid databases. They have content similar to what I would have had in the real database a year ago.