Going back to serializer's problem (quoting it again for convenience):
Originally Posted by serializer
So, we both have two pair. The game awarded Heavy the win, presumably due to his 9 kicker - but the 9 and my 4 weren't in the final hands. We both had the same best 5 cards: 10, 10, 6, 6, K. If there are better cards on the table then the kickers aren't used.
Somebody on the Steam forums said that it still announces only one winner in a split pot, but it does split the pot correctly. So most likely there is no problem here (other than the very poor announcing, as usual).