When my sim takes a photo (any camera), two photos appear in inventory. If I hang one photo on the wall, then change to a different interface (like O for Needs) and then focus back on the inventory, the 2nd photo has disappeared.
If I sell one of the two photos from inventory, then the second one disappears similar to above paragraph.
However, if I leave both photos in inventory, it stays as two photos. I haven't left the lot yet to see if it will still be two photos when I return.
On Xbox Series X.