Request a Signature (different name added)

I sent a form for a signature to be added using only the client's email address. I did not add his name to the form. However, when I sent it, it siad that it had sent to someone else (still at the right email address). So instead of just saying it had "sent to john@abc.com" it said "sent to Julie (john@abc.com)". It turned out that the name it had added was the client's wife. Any idea how/why this happened.