@scavy
Thanks for all the explanation!

I will do that.

Unfortunately, both my roms and the system are record in the same SD card (´;︵;`)

Hello @boblablah
you need to add roms (*wad) in doom folder /recalbox/share/roms/prboom

Check readme.txt

Just copy the files in the corresponding folder. You can use either .zip files or uncompressed roms. To refresh the game library, go to the Menu, then Games Settings then Update Games Lists
source : Manual wiki