By all means, bring Pola along! But make sure they meet somewhere on neutral ground where none has been before - can be bath tub with a towel in the bottom, if necessary!
If there is aggression (sustained strong teeth chattering and fighting) within minutes, you know that it is not going to work out and save yourself and the pigs a lot of stress and unhappiness.
Any rumbling (unless it is connected with the chattering) is OK, as it is dominance display. If they smell each other out and chase around, but NO chattering, then everything is going OK, and you can try and feed them a bit of grass or cabbage to see whether they will eat next to each other.
Good luck!