Originally Posted by aacharya

Use two browsers and do the work in parallel. The risk is that something happens with the algorithms when you book the revenue or the award flight and increases the fare or reduces the business availability.

In your specific case, more likely that the award gets pulled if you book a business fare ticket, so I'd ticket the award first. Or use some tricks to hold the award or the cash ticket while you book the other.

Either way, you have 24 hours to cancel if something goes amiss.

Originally Posted by Kacee

If by "same itinerary" you mean purchase the same flights for the same days, one with cash, one with miles, that's not a problem. But the two tickets (yours and your wife's) cannot be put on the same PNR (which is commonly described as an "itinerary").