The pregnancy issue is thankfully not relevant here, the only hamster hybrid so far is the Campbells and Winter White.
It will likely be possible to pair your robo with another little one as he is still young, but the rule is always only ever have as many hamsters as you are prepared to keep separately. Teenage boy robos can be very tricky, and although there are things that can be done to increase the chances of them staying together into adulthood, there is never a guarantee. Really up to the age of six months you are dealing with hormonal hams, and with boys this can go on till 18 months when testosterone naturally begins to decline. Boys will not ever live together in the wild, so it is no surprise that they can struggle as pets.
It is of course your decision, but hopefully that will help you make an educated one