This is not correct.
There are not 2 checks. There is one check to resist (except in cases where a debuff cannot be resisted or in cases where the defender is immune to that debuff, and in those cases there is no check at all).
The ONE check to resist has a percent chance to resist of (Defender's TEN minus Attacker's POT) or 15, whichever is larger.
- If my TEN is 100 and the attacker's POT is 122, then my chance to resist is 15%.
- If my TEN is 100 and attacker's POT is 101, then my chance to resist is 15%
- If my TEN is 100 and attacker's POT is 90, then my chance to resist is 15%.
- If my TEN is 100 and attacker's POT is 84, then my chance to resist is 16%
- If my TEN is 100 and attacker's POT is 75, then my chance to resist is 25%.
And so on. But it's always only one check.