Offset?

[Snake~eyes]

Okay I get the Play of the Day, you can signup here-> http://www.nafoa.net/PlayOfTheDay1.htm





A fight breaks out between several opposing players and: (a) two substitutes from each team come onto the field; or (b) one substitute of A enters and three enter from B's team box.
__________________________________________________ __________________________________________________ ____________________________________________
Ruling: In (a), both substitutes are disqualified and the penalties offset. In (b), the one 15-yard penalty on A will cancel one by B resulting in two 15-yard penalties on B. In both cases, penalties and disqualification also will be assed to those who where fighting. (9.8.1)Casebook (2.11; 9.4.1)Rulebook


My question, do the penalties really offset? I thought they don't :/