We have given up on double bags and use singles now. The wife is a heat vampire and her cold feet suck all the heat out of me.
She uses a carp fishing bag which is big enough for her to get into starfish mode. I use an ex army arctic bag. Both are not restrictive and are nice and warm.
For backpacking we both use mummy down bags made by Kelty
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.