Patient think they watched something before

My mom has dementia. When we watch television with her she is always saying she has seen the show we are watching before. This is generally impossible because it is a first run show the first night it airs. If we explain this she gets very agitated. Does anyone else think they remember things that are impossible to be remembered?

Thanks. I meant to say did any of their loved ones do this

I have recently noticed that my gmother remembers past events with imaginary parts that totally never happened. This is new. She was diagnosed in 2010 as early stages; reevaluated yesterday as slow decline. We are now having to get her to understand that things need to change so she can be safe and continue her life living independently, just not alone. Paranoia is present. Delerium nearly. Since the Dr. appmnt. It appears that the extreme stress of accepting this is causing a severity of the symptoms. This is still new to use because after one Dr. said it was, another said it wasnt. Now the MRI says it is.

Sorry to have run off topic. yeah it seems to me that her imagination trys to improvise for the loss of memory. I will definitely focus on "going with the flow" when possible.