Nah, same one. Fifty thousand colonists -- no one thought they'd be stranded. But the wormhole collapsed behind them, so they ended up stuck on an unterraformed planet until the rest of the galaxy stumbled across them. About a hundred years ago? Something like that.

( well it's not like they got along, but it certainly wasn't divided amongst ethnic lines, unless you counted everyone's general dismissal of the greek speaking population. )

Anyway, the galaxy finds this planet that's using horses and swords instead of proper weaponry and thinks it's an easy target for conquest. So we fight it out for about twenty years, and eventually they just give up. Er. Not without killing five million of us and nuking Vorkosigan Vashnoi. Ask Miles about that, his grandfather willed the damn glowing crater to him.