Maybe identity theft?

Yesterday "I" received an email from apple (confirmed it legitimately is from apple) saying that I was almost done setting up a credit card in apple wallet. However, I am not doing that. Someone else is, apparently.

So, firstly, I'm a little unclear about what is going on. Is someone using my email address only or my email address and my apple account to set up a credit card in.... someone's wallet? I checked my wallet and it only has my cards. Is it possible for there to be 2 wallets with one email address (mine) and I can't see the other wallet?

When I search here on apple.com for information about my account, I only see my devices associated with this email address and I've never used a different email address to set up anything with apple. I also haven't been charged for any purchases I haven't made - confirmed in wallet, my bank and apple.com receipts.

This seems like some sort of identity theft using my email address, but I can't determine what is actually going on.

Does anybody have any insight into this? It'd be much appreciated :).