Lira - I don't know where you read the info "does not open..." these "joker BF keys" (as I call them) => do not open an ADDITIONAL level.
Now, imagine, you would find the real BF key first and then the 2nd one. For whatever reason you return to your starting level and find this joker key => it opens the 2nd lvl then (the same, the highest, you have achieved). Imagine, you find the 3rd key in Sammy's lair and return: then this joker key would give you the info => 3rd level is unlocked.
I thought about "chameleon BF key" first, but this word is more difficult to write <img src="/ubbthreads/images/graemlins/shame.gif" alt="" />
