The smarter part of my brain suggests that regardless of probabilities, each event is mutually exclusive and two failures could absolutely occur on the one flight and that could be just after takeoff, over water or anywhere for that matter.
If you had told me that five 0’s were going to come up one night at Crown Casino on Roulette, I’d never have believed you, but it did happen.
I feel as though the Swiss cheese effect is more likely to cause the twin failure (at different times on the one flight), rather than 2 x compressor blade / actual physical engine failures for example.