After there has been a fight and bites then it is unlikely for two piggies to go back together again.
They have to reestablish their hierarchy in a new environment so while they were ok at the shelter, bringing them home would have meant they go through the restablishing. That can bring any underlying issues between them to the surface and then be too much for them to overcome.
That reestablishing takes up to two weeks which is why the fact the fight happened at the end of the first two weeks may be significant as an incompatibility
Sometimes boars just get to the end of the teens and suddenly decide they don’t want to be together - it doesn’t happen as often as fights during the early part of the teens but we do see it occasionally happen. Lack of space can exacerbate both those issues but not necessarily be the main cause.
So whether it is down purely to the cage size is unclear. If it is due to underlying tensions or an incompatibility then those issues don’t go away so a larger cage in that case will not make a rebonding successful.
If it was a momentary tension that would otherwise have resolved by one moving away, but the lack of space meant they couldn’t get far enough away so it resulted in a fight, then maybe they will go back together.
If you wish to try then you of course can but you must make sure you go through the full and correct neutral territory bonding process. You would need to keep a very close eye on them, not only during the few hours in the bonding pen but for the whole of the two weeks after (if they do go back together) as it is during those two weeks that they fully form a hierarchy and it can fail right up to the end of those two weeks.
If you were going to try it, then you need to make sure any cage you intend on them living in together covers 180x60cm. (Do also remember that thar cage size isn’t big enough to split in half if it fails again - you need 240x60cm to be able to split in half so each piggy ends up with 120x60)
The guide below explains the neutral territory process
Bonding and Interaction: Illustrated social behaviours and bonding dynamics