In breast feeding multiples the logistics get a little bit tricky. It definitely still works out, and there are many different holds, but your supply will remain strong for however many babies that you're feeding. If you're feeding twins your body will produce for twins. If you're feeding triplets your body will product for triplets and so on.
Your body learns from the amount of stimulation that it's getting how much it needs to produce. It's an issue of supply and demand. That's all it is.
With positioning for twins, it's really very simply once you get the hang of it. Typically, if you're feeding both at once, there are many different positions but you could put both babies in two different football holds. There are moms who feed one baby and then the next right after. It really depends.
Also with many twins one baby maybe stronger than the other as far as the suck is concerned and so a lot of times I recommend to my mom's, and also for purposes of not being confused during the day as to which one had which breast, to give each baby one breast per day and then let them switch for the next day.
Usually the baby with the stronger suck will do a lot of the work to bring down that milk for the baby with the weaker suck for the next day. But your body will produce enough and your babies will be able to be sustained by your breast milk supply from just their own stimulation.