I may be mistaken but I don't think Bitcoins (the units themselves) have an identity like that only wallets are entities. It's similar to how a celebrity would

I may be mistaken but I don't think Bitcoins (the units themselves) have an identity like that only wallets are entities. It's similar to how a celebrity would drink water and water would be worth more than the rest. Once the debit and credit occurs who is to say which coins are from what source...