Neither the manual nor the program make it clear what happens when one backup overwrites another

[LinuxOnTheDesktop]

Describe the bug
Neither the manual nor the program make it clear what happens when one backup overwrites another.

Expected behavior
It should be clear what happens when one backup overwrites another, i.e. when, if one makes a backup (say, a full backup)to a location, and then runs another backup (say, again, a full one) to that same location (as one might do by making use, via cron, of aptik's admirable scheduling features). What does happen?

System:

• Linux Distribution Name and Version: [e.g. Ubuntu 16.04] Mint 19.1
• Desktop [e.g. MATE, XFCE] Cinnamon
• Application Version [e.g. v18.8] 18.8

I apologise if in fact somewhere the information in question is provided.