Sideboards can help the AI decks a lot, and I really think we should take advantage of them when we build enemy decks. However, if you play with e.g. two colours, both the sideboards against those two colours will kick in. Not sure about the exact mechanics, but it definitely happens.

This leads to two problems:
- It can make enemy decks have >4 of a certain card, which is sort of cheating
- Enemy decks often end up with more than the intended number of cards, making them weaker (and often unbalanced when it comes to mana production).

So if it was possible to make the game pick only one sideboard (primary player colour), it would be an improvement.