I see 3 ways to use opposed rolls in MRQ2 :
First option :
You can state that parry roll needs to beat the attack roll in order to block any damage (that was more or less MRQ1, revised).
Second option :
You can give an extra Combat Maneuver to the winner of the roll.
If this sounds too deadly for you, you can chose to give the extra CM to the defender only.
That is, you can chose between :
Attacker is 2 levels of succes over the defender : attacker gets 3 CMs
Attacker is 1 level of succes over the defender : attacker gets 2 CMs
Attacker and defender have the same level of success : Higher roll gets 1 CM
Defender is 1 level of succes over the attacker : defender gets 2 CMs
Defender is 2 levels of succes over the attacker : defender gets 3 CMs
Or :
Attacker is 2 levels of succes over the defender : attacker gets 2 CMs
Attacker is 1 levels of succes over the defender : attacker gets 1 CM
Attacker and defender have the same level of success, Attacker get the highest roll : No-one gets a CM
Attacker and defender have the same level of success, Defender get the highest roll : Defender gets 1 CM
Defender is 1 levels of succes over the attacker : defender gets 2 CMs
Defender is 2 levels of succes over the attacker : defender gets 3 CMs
Third option :
Latest MRQ1 playtest rules stated that in case when success level were equal, defender would block APx1 Damage if he got the lowest roll, and 2XAP if he got the highest one.
In MRQ2, this would be equivalent to give one extra size to the parrying weapon.