There's a discussion in the comments for Vash the Stampede's 'Life's regrets' where he says
"I distinctly recall reading about people who could time travel through body-swapping. The part that really stuck with me was the main character dealing with someone who had swapped so many times that they ended up existing in both their own body and their wife's body at the same time."
Anyone have any idea what story this would be? Sounds like a great mind-fuck!