Bunny Bonding
Rabbits are happier when they have another rabbit to love. While some seem to want to stay solitary, especially if they have bonded to their human, most bunnies prefer the company of their own kind. It also gives them company when their humans aren't home. Typically male/female bonds work best. Then male/male and female/female. Remember, they are a female dominant society. Some rabbit experts believe that male/male bonds tend to break if they are from the same litter.
As with humans, rabbits want to pick their own mates. Members can make an appointment to bring their rabbit to the shelter for a bunny speed dating session. This way, your rabbit makes the call. When you find a rabbit that seems interested(grooming, sitting side by side, not fighting), you can bring your rabbit back for future dates. If they seem to be going well, you can adopt the new bunny, however, it must have it's own cage/pen/space. You cannot automatically assume that rabbits will want a stranger moving in with them.
Set the cages next to each other, but leave space so they cannot touch to prevent injuries when you aren't around. You can also switch litter boxes at every cleaning to get them used to each other's smell. Have dates everyday for your bunnies in neutral space. Try a couch or even a bathroom where you can monitor their behavior. Only when they are spending several hours a day with each other without any fighting and able to share food, should you attempt moving them in together. Clean everything in their cages before putting them together. If they both have small temporary cages, you can even get a new cage to put both of them into together--this prevents territoriality. You could also move them to a pen since they will need more space.