The same basic principles apply to lactation whether you have one or three suckling. The challenge with more than one baby is positioning and scheduling.
Positioning: the football hold works the best, so you can feed both babies at once.
Scheduling: if you want to provide both babies with exclusive breastmilk, then you should make every attempt to feed the babies at the same time. Many moms think pumping and bottle feeding one and nursing the other will be easier but it absolutely is not. Pumping does not empty or stimulate the way a baby will, so this action can result in low milk supply. Also, if you introduce a bottle to early, many babies will begin to be lazy and even refuse the breast because it is more work for them.
Can exclusive breastfeeding be done with twins? You betcha. I recently met a woman who exclusively breastfed triplets. Not one drop of formula for any of her three babies. Now that is superpowers.
Another great tip, is to get a TWIN breastfeeding pillow. Not all pillows are created equal:
This is a great video of real babies latching on, it is in a foreign language but the visual speaks volumes on its own.
Here is another video on how to coordinate feeding two:
Having two or three babies at once and breastfeeding is indeed possible and preferable.