Is there a trailer for a bike that can pull another bike?

Not that I know of, which isn't saying that someone might have built one anyhow. What you can find though are trailer bikes. From the handle bar and back they look just like a regular bike, but where the front fork would go there's instead a long extended gooseneck which connects to the seat post of another bike in front. Often used by parents whose kids are too big for child's seats but too small to ride for themselves. Then there are towing systems used by expedition racers, letting a stronger rider help a weaker team member. These rely on the person on the towed bike still being able to steer, balance and to provide some power. If you want to be able to tow another riderless bike I think your best option is to look at something like the Bob yak trailer but having it attach to the front fork/hub of the bike getting towed.