from what i understand (and what makes sense to me) some hedgehogs will get jealous of new cage mates. Optimally hedgehogs that are housed together should be litter mates (2 females of a litter) or a daughter/mother. Introducing another hedgehog to a previous hedgehogs home could be seen as an intruder. Also you would ahve to have 2 of everything in the cage, as fights over food/water and toys will likely happen with sage being jealous/concerned.
On the flip side they could be best of friends and never have a problem. It is all a gamble.
I would say if you were going to do it, to have a separate cage just in case. Start off by having them in separate cages for a month (isolation period) where they can still see each other. Then try moving them into a same cage with a divider in it so they can see and sniff each other but not hurt each other. After that i would suggest doing a supervised play time every day. After a while remove the wall during the day and leave it closed at night (when they are active they can't interact, when they venture out for food during the day they will see the wall is gone). Eventually you should be able to remove the wall for good, but you will need two wheels, two food dishes, two hiding spots, two toilet paper tubes, who water dishes/bottles as they will likely not share or fight over them. Also if you plan on putting two where you keep 1, you may not have enough space for both. You will need much more space so they can keep isolated if they wish.
At any sign aggression, even a nip or headbutt, i don't think it will work out and they will have to be seperated. It is difficult to force them to like each other, and may just cause one pain.