In Archicad go into the HELP menu and look for either "Downloads", Add-ons" or "Goodies".
Sorry I don't have Archicad in front of me at the moment.
You want to download and install an add-on (or Goodie as it is sometimes called) called "Check Duplicates".
This will do what you are looking for so long as the elements is an exact duplicate - for any element type - lines, fills, walls, roofs, etc.
Also if it is just lines and fills you are worried about then you should have line consolidation and fill consolidation tools in your tool bar and menus.
These can be more powerful than the check for duplicates as it can combine overlapping lines and fills rather than deleting just exact duplicates.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11