Six friends Andy, Ben, Carl, Danny, Ethan and Frank were hanging out when Frank spotted a wallet lying on the floor. Frank does not have a good memory, but he remembers that the wallet was owned by one of his five friends.

The following are the statement made by the six friends:

Frank: Whose wallet is this?
Andy: That's mine.
Danny: You're lying, Andy.
Carl: Yeah, Andy, you are lying.
Ben: Andy is not lying, guys.
Danny: That wallet is owned by Carl.
Ethan: Yeah, Danny is telling the truth.
Ben: No, Ethan. That's your wallet.

Frank remembers that at least 2 of his friends are the knights who always tell the truth while at least 2 of them are the liars who always lie.
However, Frank cannot recall which of his friends lies or tells the truth.

Can you help Frank to determine who actually owns the wallet?