I have two twin bunnies – one boy and one girl.
The male has a SLIGHTLY smaller head but sometimes I have to check their ears to know who is who. My three rabbits that are identical are from a breeder so they were all given tattoos as babies. Fleury was never shown so he doesn’t have a tattoo but his sister and brother both do so I have had to used that to tell them apart before! I would look for small differences, maybe a SLIGHT difference in pattern. You could always do something with their fur to make one have a slightly different hairdo if they are longer haired buns. I’ll see if I can think of anything else unique to do and post if I can!
There is no way to really track their eating besides just glancing at them to make sure they are both getting their share and no one is hogging them all. My bonded buns never wolf down their pellets, they eat randomly throughout an hour or two of getting pellets so I have not ever had to worry about someone not getting their share. You can also weigh them weekly/monthly to ensure no one is losing weight. All my rabbits get about 1/8 cup pellets so I know if someone gets a little more or less than their share, it won’t affect their weight or overall health. I do have one that has a problem with keeping on weight and needs 1/2 cup pellets by himself to keep on weight so I feel him the normal share of 1/8 with everyone else but then I feel him Critical Care mixed with pumpkin and carrot juice to supplement his diet to make sure he doesn’t lose weight!