If I do not have room to separate them, I will probably have to rehome one correct? Also, is it always going to be hit or miss with a new piggie? I don’t want to have to keep adopting new ones and if it doesn’t work out, to have to put them back up for adoption.

Poor guys you know?
Separated piggies need to be side by side (120x60cm minimum each) so if you don’t have space for two cages or cannot split the one they have in half to give them each enough space , then rehoming one may be the decision you have to make - it does need to be your decision though.
Two piggies have to have character compatibility for a bond to work out. If you can surrender one to a rescue for rehoming. Also see if the rescue offer dating for the piggy you choose to keep. If he can have a date at a rescue centre with other piggies to find a friend, then you can be reassured of compatibility - if they can choose each other then they are more likely to have a long term bond. You then only bring home a new piggy if your piggy has accepted with friend - you aren’t then left in the position of failed bonds.
If you buy a piggy from a pet shop or rescue on spec without dating first (some centres will want you to take the piggy home, try to bond them yourself) then there is going to be the risk that they wont have compatibility and the bond will fail. however, the benefit of bonding on spec but with a piggy from a rescue centre is that they will often allow you to return the piggy if the bonding fails and allow you to try another one until you find a match. You are unlikely to have that option with a pet shop - you will be in the same situation with two piggies having to live side by side/having to surrender one you’ve just bought to a rescue
Bonding teenage boars with another boar is harder due to the hormones, but not impossible, but this is why a rescue centres help is valuable.
Pip is likely to be harder to bond due to the fact he is at the height of hormones. They are teenagers until 14 months of age but even up to 18 months can be trickier.
The alternative is to neuter the one you keep, have the six week wait and then bond with a sow. Neutered boar/sow bonds tend to be more stable long term but they do have to have compatibility to begin with.
A boar pair require a larger space - 180x60cm cage - whereas a Neutered boar/sow pair can live in a 150x60cm cage (recommended size - but 120x60cm is the minimum for a sow/boar pair)