This is 100% my fault. I messed up when it was first announced and listed them separately.
Since US pre-orders immediately get assigned to games as soon as I hook them up, if we were to create a unified entry now, we'd lose those sales. So it's a catch 22 atm - unify them but lose the pre-orders, or keep them separate and maintain the sales.
I'm kind of jumping the announcement gun here, but next year we'll be listing shipment data on game pages, which will allow us to resolve this issue (along with several others!). But for the next two months we'll have to track them separately.