Originally Posted by
saddlesores
okay, i give, you're right. he didn't have two trailers. he had a bicycle towing a thing with one wheel,
towing a thing with two wheels.

so "technically" he wasn't towing two trailers; the first trailer
was towing the second trailer.
I wouldn't consider a tagalong bike a "trailer" personally. Therefore my point. Some Googling of the matter shows it's rather safe though. Much more positive reviews than negatives.
Here's an old thread from here
http://www.bikeforums.net/tandem-cyc...insane-no.html