We also lamb some hoggs, generally lamb easily, although if they are carrying a single that has gone a bit over large they may benefit from a little help. Agree re having them penned to mother on, have found with twins if one wonders off at lambing time it can be harder to get them to take both, so best to keep them close to mum. We find the mums are very good once they have got the idea of what to do, if somewhat ticklish about their udders at first.
Quite a few of ours do have twins, last year they all did, we took some off, but the last few to lamb kept both lambs, we make sure that the lambs have access to adlib creep feed to help take the pressure of mum's milk supply, and also feed the mum's well after lambing, they should have less feed than an adult ewe prior to lambing. This year we are going to wean the lambs at around 6-7 weeks old to give the mums plenty of time to recover and grow on through the summer.