Yep. This seems to be common.
One old memory I have always seemed crystal clear, but just today I realized that I must've confused one little detail (which had to do with left-right perspective).
Other people do this, too. Sometimes, a friend or family member will insist you did or said something that you know you never did or said. You can tell they're mixing up different conversations. Then they spread misinformation. Or they'll insist you weren't somewhere, even though you remember being there.
Like Judge K., I kept detailed calendars for many years. Whenever anyone (loved ones) would insist we went somewhere, or didn't go somewhere, or whatever, the calendar would settle the argument.
I don’t accept the premise that she’s a victim of anything other than her personal demons. These are “recovered” memories from her session with a family counselor that we’re now seeing happened in a different year than she claimed. Here’s a link to a video about how easy it is to implant a false memory: https://youtu.be/58AxIGmjEP4. As a hypnotist, these are techniques that I definitely know how to implement.