Congratulations on your new buns! They’re adorable!
Most rabbits (there are exceptions) prefer living with another rabbit, especially rabbits that grow up with another rabbit.
Rabbits are however a highly territorial species (an adaptation that most likely is due to the fact that wild rabbits spend a lot of time and energy on making their complex warrens). This means adult rabbits can, and most likely will, fight with stranger-rabbits.
Baby rabbits won’t fight, the problem arises when the rabbits hit puberty. For this reason, and in order to prevent the buns from multiplying (if the buns are of opposite sexes), the baby buns should be separated at age 12 weeks, before any bad fighting has happened.
The buns should then be spayed/neutered and given a few weeks to heal from the procedures. After that, it’s time to reintroduce the buns for proper adult bonding. This as a rule goes very well if the buns were separated before they had any major falling out. We have a bonding section where you are welcome to post about your specific buns when the time comes! You can also prepare yourself by reading in that section, to get a general idea of rabbit bonding.
Baby rabbits are notoriously difficult to sex. Even vets are often wrong. Come puberty, if you see testicles, its a boy – obviously- but rabbits can “suck in” their testicles so they don’t readily show during a quick inspection.