Can you rent two uhaul trailers with one car?
Why don't you just rent a larger Uhaul truck and do it all in one load?
No, there's no way to hook two trailers together.
I'm not sure what that would save you. If you hang the trailer on its intended car in the first place you don't waste any time changing trailers.
Talk to U-haul about that. Both vehicles would need to meet the minimum towing GVW limit for the trailer you want to rent, and your friend would have to meet their insurance requirements.