Our Family just got 2 young Goats one Dowling and one buckling at least that's what the man we bought them from called them they are about 6 months old.
If you are housing them together you need to rethink that.
Bucklings, depending on the breed, can breed by 8 weeks old.
Doelings, depending on breed, can cycle into heat by 12weeks.
You would not want them to mate at this age as it could kill your doeling.
If you are not going to breed the buckling then it would be best to "wether" him. That means castrate him. Then you can keep them together. If not then they need to be separated and each one will need a buddy.