I suppose you could for a while but you should expect mating when they get older, I have had two males living together for 5 years now and they seem to be fine, not sure about the opposite sex though. It's cheap enough to house them separately, a 50l rub is a perfect size for a royal( really useful boxes) is the make I would suggest, will probably set you back 15quid a tub.
02 Corn (female) 03 Amel corn (male) 03 Amel corn (female) 03 Royal reduced pattern (male) 05 Royal normal (male) 09 Het Pied (male) 10 Royal normal (female) 10 Het Pied (Female)