In yesterday’s game BLR–FIN, at 59:16 with Belarus trailing 0–1, Belarussian player injured a Finnish player with a high stick, and received double minor penalty (2+2) for that. However, during the same game interruption, a Finnish player received a minor penalty for roughing (because he avenged the injury). (See the official game summary sheet.)
Normally, I would expect a four-on-four play be the result of those penalties (and normally, after two minutes of 4–4, a two-minute power play against Belarus). However, the referees sent two Belarussian players to the penalty box (and the Finnish player), and the play resumed with 5 Finnish players against 4 Belarussian.
I am unable to find any rule which would govern that situation. Can somebody explain that, or was that just a referee error?