I had the same thought for a split second, when I realised a camping load for two wouldn't go into my Edinburgh Bike Coop single wheel trailer. In theory you could put a spindle throught the wheel of the trailer and tow another. In practice, I got into a couple of snakes with the one trailer, I wouldn't fancy it with two, I'd be waiting for the trailers to overtake me. I certainly would't risk it with a child on board.