I am slightly surprised that none of the experts out there have answered in all this time.
It sounds like a trick question. The obvious answer is "one" because ACAS can only offer a single RA instruction - albeit one which may modify as the situation develops. However the fact that, under some circumstances, the RA may be reversed does suggest that a second manouevre is being calculated in the background and then the reversal occurs as the system decides this is the preferred one.
However ACAS logic is not my strong suite and I offer this only as conjecture.