On retail using same speed weapons, you would get 4 effective flurry charges rather than 3. Both your main-hand and off-hand would swing at precisely the same moment and the last charge would apply to both the main hand and offhand. I've tested this with two 1.30 speed daggers and using attackbar you could tell straight away something was off since the two swings weren't synced and instead there is a built in delay between your main-hand and off-hand swing.
I suppose it's some kind of botched work around to prevent situations like this arising, however it's not blizzlike at all. This also prevents anyone brave enough from swapping his mainhand and offhand for double windfury since the unsynchronised swingtimers wouldn't make it worthwhile.
Even with AQ being delayed this is hardly a pressing issue and devs might not ever look into this, however I think it's important enough for some people to put this out there.