Two People One Hammock,you would think that each person would be rolling into the other, but in essence this really is two separate hammocks with a simplest shell over it and a piece of fabric between them. While this set up offers new opportunities it also presents a few challenges. On the top of that list, picking two trees that are two far apart and then sitting down! Due to the way things like gravity and physics work, if you tie up to trees that are too far apart and put weight on the hammocks, each will want to naturally swing to the shortest point between it's supporting trees. Since the Hammocks only have a limited amount of slack between them it's possible for the two peoples' weight to destroy the trough between the sleepers, but also the roof.
This provides a simple but effective solution is two tie a piece of strong rope loop to allow the two hammocks to only move apart from each other a predetermined amount. I'm experimenting with using a rope ring in the middle then using it to help with adjustment. This same principal works the other way too! So long as the head end trees are too too close you can use an actual spreader bar tied outside the hammocks on the head end will keep the two sleepers the proper distance apart. Both of these methods increase strain on the rope, but I think that the hammock is not effected in the slightest.