Contact Form 7 and Akismet question

I’m using Contact Form 7 and Akismet, but on my contact forms, I have fields for the submitter’s first name AND last name; I don’t use just one field for “Name”.

Could someone tell me which field, then, I should define as akismet:author field? first-name? last-name? Neither? Does it cause a problem for me to break up the name into two fields?

Thanks in advance.