I also still have the old FOID card along with my CCL. Recently was going thru a private sale and gave my FOID number and DOB to the seller and he immediately sent me back a message saying I was giving him a bogus number because it had less digits than his FOID. After explaining it to him and telling it him to just run it, ended well. Moral of the story is, not everyone with a CCL was issued a new FOID