First, you're assuming that people know about gaffed coins. People may assume trick cards, but the only gaffed idea I've had thrown at me was "magnets". I don't think people are any more impressed by the chips than the coins themselves. Then again, that's just my opinion.
As for dropping one chip and it multiplying, there are a few ways I can think it with out gaffs. Edge Grip would work pretty easily, but my recommendation would Classic Palm. Just drop one from the fingers as you drop one from Classic.
The Coin Dumper dumps 10 coins into a finger palm with a very small amount of movement. I've only found them in half dollar size though. I didn't find what's called a Coin Holder, which holds out 4 halves, but can stretch. I haven't tried it, but I'd assume 2 chips would fit and could be concealed in the sleeve.
I just realized that my comment on the gaffs came out wrong. What I meant is, a poker chip is something that everyone has/have had at one point in their lives. Also if I do a lot of card tricks it would make sense to have some poker chips. IMO the one problem I always had with half dollars and centavos and other coins like that is its something that not everyone has let alone brings with them. I know most people don't carry poker chips with them but thats my logic for ya!
The whole dropping a chip and it multiplying into two happened by accident. I had a stack of chips and accidentally dropped what I thought was one, in fact it was two chips stuck together. It fell as one chip and only separated when it hit the table. It looked amazing to me because I wasn't expecting it. The chip fell as one but when it impacted it bounced up as two. I want to replicate that effect again w/o it being obvious I'm holding two chips (which is obviously much thicker then one)