No, they don't care. They only ask "primary" and "secondary" because that is the order that they'll hand out the records in response to queries. It's the same terminology used in configuring zones, but it's not the same thing. If you would like the secondary server to handle the bulk of the requests, then tell them that's your primary. They'll never know the difference, nor will they care.
Glad I could help.
-exx
