The movie, if i remember correctly, was about a guy, who has a creature/monster in a cage that could duplicate things that you set on fire in front of it. e.g. burn money in front of it, it makes lots of money appear. But, something bad also happens when you do it.
the darkling?
I remember watching the movie when i was a kid. Late 80s or early 90s. So unfortunately no, thats not it.