Referral program without referral offer feature

We haven't yet subscribed to the referral offer feature, but would like to run a small referral program with our clients. I tested the program using a standard form, just changed the hint text to indicate that our clients should enter their referral information rather than their own information - the issue (probably obvious to folks using Marketo longer than I have) is that when I entered fake referral contact information into the form, it is overwriting my existing information in Salesforce with my fake referral information rather than creating a new lead. 

Wondering if anyone has suggestions on a better way to do this. 

Thanks!