I have a family that is a father, his teen daughter, and their cat.
Travis(father) died when he was repairing the TV. The daughter, Takara, has the correct memory of him dying, but their cat has two. One says:
"Travis Died 'This sim was so close to me, I don't know how I can go on without them. Only time can ease my pain...'" the other says "Travis died 'Life is so short, one minute you're here, and the next your gone. Really makes you think...'"
Why does the cat have two memories of it?

EDIT:
Another thing: I moved Travis' tombstone to another lot. Would this create a new memory for them?