An interesting idea Margaret.
I can't say I have any experiences to add that illustrate this theory.
I do know that when we remember something, it is from our own perspective.....so my sister and I may have been at the same event, but our memories of it will be very slightly different.....because our perspectives are different.
The core substance.....such as the time place etc will essentially be the same, but our memories of it will not be the same.
I know that this isn't what you meant.....but it is all I have.
If your theory about existences in parallel universes is true.....then why is my current life so hectic in all of them?
Couldn't just one of them allow me to be somewhere nice, sunny and warm......with good company and a glass of something cold to sip on(not necessarily alcoholic)
!