That's not necessarily how they'd greenlight a sequel though.
Dark Arisen is potentially seen a lot like selling DLC to the same people. Similarly I didn't combine Super Street Fighter onto Street Fighter IV or DR2:OTR onto DR2's total.
Street Fighter is tough because some of those iterations are meaningful. Combining SF4 and SSF4's numbers is probably okay (maybe even Ultra's). Retail copies of everything after that though, not really.