Please help me identify this plot device

[IndridCold]

I was watching a film last night, and there is a female character who cannot understand her husband's mood changes. It turns out she is married to identical twins.

I am sure that I read this same plot in a book, but cannot remember which one. It's definitely not the book of the film.

The Prestige? Fantastic film.

What was the film called?

I googled and there's a book called Deceptions, but that's female twins swapping places.

Yes, it was the Prestige , didn't mention it in case people hadn't seen it.

But I'm sure that I've read that same twist in a book too.

No, not Deceptions.

Dead Ringers is another extraordinary film that is based on the same premise. A younger Jeremy Irons plays both twins

It's sort of in one of the Number One Ladies Detective Agency books where a Dr and his twin are swapping about. One is qualified, one is not.

Double Take by Brenda Joyce?

Ah no, that's sisters again.