Pigs will eat more then they need which will make them run to fat quicker then you think. Pigs will naturally root around if they need more food.
If you are going to have an automatic feeder then i would limit it to a set amount a day. Preferable in two feeding session but one can suffice. Also you would have to make sure that they both get the intended feed. I say this because one pig could (and probably will be) the dominant one and therefore 'steal' the feed of the other one. I see this a lot on the pig farm i work on when the sows are in the dry paddocks. The dominant sows just bully the others out the way.
If you can, then feed the two pigs apart so they can get their own feed without stress.