You only need one food bowl. You should have two water bottles (even with one pig), but water bottles have no impact on cage space. Actually, you can get creative with hidey spots that don't take up as much space. It doesn't have to be two pigloos.
There are many many threads on here where someone asks what size cage to build and people tell them that for 2 boars, the minimum should be a 2X4.
If someone asks what cage size to build, then yes, I agree, I would recommend a 2x4 for boars. I go back to the point that I really don't like to see anyone criticized for providing a 2x3.
Personally, I would recommend a 2x5 for 2 boars. So, where do you draw the line? The point is not to make someone feel bad for doing what this site recommends. If you want to criticize someone for a 2x3 then, you really need to criticize me. That's what should be going on. Not telling new, excited members that they screwed up. Most people evolve their cages over time anyway.