With a picky pair like this I don't prepare two feeders, I only prepare one. If the first snake doesn't eat then the feeder is rewarmed and offered to the second one. If the first snake eats then I prepare a second one for the other snake, and it's not like thawing and warming a rat pup takes a very long time.
Also I would put these guys in a 10-14 day feeding schedule. Snakes in captivity are often overfed and most really don't need to eat every week, though many will simply because they're opportunistic and instinctively they know that it may be quite a while before the next meal comes along. In the wild they would not eat as often and they would expend energy hunting.