Is copying others common?

Hello,
My father has started copying everything I do, including (but not limited too):

- Wanting to buy the same dog I have
- Taking on interests I have
- interrupting my sentences to say "me too" even if it makes no sense (I love being a mom.."me too!").
- Taking on my husbands interests, and spending large amounts buying the same things he does.

He seems to do it mostly with my family and I, but also does with other family members and sometimes celebrities.

Lliterally anything I tell him, he seems to uncontrollably say "me too" and then within a day does or buys the same thing I mentioned doing/ buying.

I noticed it's gotten so bad that its impossible to even finish a sentence without him saying "me too", and this scares me that something is advancing within his brain.

I am just wondering if this is common for Dementia, or may be related to his ADHD and other conditions. I can't seem to find a name for it anywhere.