Oh! Yes, sorry. I also see that I misread the whole thing, and got my own rules wrong (Grapple Rules: the bane of many an RPG developer)...as it seems a reversal CAN happen if the defender succeeds and the attacker fails.
That being said, in the event of a success by both, what it basically means is that they are still struggling to gain the upper hand. The successful attacker needs the defender to fail to achieve a grapple, while the successful defender needs the attacker to fail to turn the tables and grapple the attacker. Otherwise, they are locked in combat, inflicting no damage to each other (as their efforts are being spent trying to either attain a hold, or prevent one). The MoS doesn't matter in the event both fail or both succeed. (Though, if I were the GM and saw them both fail, I might try and make it look a bit silly, like two wrestlers who charge each other and somehow fail to connect because one reached too high and the other stumbled and ended up dropping to a knee.)
Think of it like one of those old-school, Original-Series Star Trek melees between Kirk and the enemy of the week. When he and his opponent stand there, at arms' length, unable to grab each other's bodies or necks because they're basically just locking arms....that's a result where neither side failed the grapple. When suddenly one of them breaks the arm-lock phase and suddenly they manage to get their opponent around the throat and chest long enough to deliver some dramatic one-liner, that's when one has succeeded and the other has failed. And when both fail, that's when a shirt gets gratuitously torn or something.
Hope that helps. And I apologize for my earlier wrong answer.
- Herb