When we first got our goats, they were from the same breeder, but were not penned together. They were an alpine and a pygmy. At first they were butting at each other, but after a couple of hours/days they started to work together to try to get out. They are now best friends, and whine while i take one or the other out to milk her. The only thing that you should be careful about when putting goats together, is make sure that the kid on the mother is big enough to fend for herself, or that she is big enough to get back up if she is hit and falls during one of the mother's tussles.