It's strange Bjorn, I measured my two dual shelf '56's and there is only 1/32nd less center cut on my 60", 60# '56 Kodiak than on my '57. The '56 measured 1/4" from center to the '57's 7/32nd's.
The common misconception seems to be that the '57 is a better shooter because of the single shelf being more center cut than the dual shelf Kodiaks but they are pretty close, much closer than I ever realized, and shoot basically the same for me.
I do prefer the looks of the '57 over the '56 but my '56 is still my go to bow, plus I can't see the other shelf when shooting anyway!