It all depends on the terrain. On open ground the Warhammer has the advantage, but if the Victor can get to medium range then the equation changes. The Warhammer doesn't have the armour to take AC20 rounds for long, and while that extra armour doesn't seem like much the fact that damage is split into 2 lots of 10 as opposed to 1 group of 20 makes a significant difference.
In a city the Victor is one of the ultimate mechs and can take on anything if well piloted areas.
2 PPCs is a less focused punch than 1 AC20, but you have a chance to hit at least once, but if you miss with AC20 you miss it all)
Anyway it's all about conditions, skill and luck)