I had the same wear on my Trailwings, I've seen it before, the compound on the front isn't dual, the wear is down to the way the tread hits the ground on bends. You'll find two things, there's more wear on the outside of centre than in the centre itself, this is because when the bike is upright there is no real force on the tyre, it's just rolling in a straight line. When leant over it's still rolling, on top of that it has some lateral force to deal with, and also more weight pushing down on it because of centrifugal force, so it wears more on the sides. The uneven block wear occurs because the leading edge of the block hits the ground first, this edge wears away faster than the rest of the block. It's this edge that cuts through water to hit tarmac to give you grip in the wet. This is why heavily worn, but not necessarily illegal, tyres don't perform as well in the wet as newer ones.
Also, the uneven wear can be exaggerated if you brake into bends while leant over, this provides a fourth force for the tyre to deal with. For example, I used to ride with a chap who wasn't confident with right hand bends but loved lefts. He used to comfort brake into rights only. The righthand side of his front tyre was shot before the centre and the left. Doing a lot of clockwise or anti-clockwise trackdays has the same effect.
Uneven wear on a front tyre is as normal as squaring off a rear.
