Yes, pen them tight while they get used to each others smells. Then a bit more space, then a bit more, and so on. Once they have more than about 8' and are behaving, then they're best outside with room for the weaker to get away from the stronger - but still watch for an hour or two just in case.
This for any tups whether the same breed or not.
In terms of tups of a different breed, it depends on the breeds. Generally don't mix horned and unhorned tups; a Swaledale will kill a Blue-faced Leicester, for instance.
Some breeds are very laid back (eg Ryeland), some just use useless at fighting (Texel, Beltex.)