How do I DISABLE Duplicate Check in insertRecords

How do I DISABLE Duplicate Check in insertRecords

If a user fills out a form, say a Product Info request form (my form, not zoho's web-to-lead form [many reasons why I'm not using this option]) and I take that info an insert a lead in my account, it works great.

If the SAME user fills out a DIFFERENT form, he will use his same email address, of course, and when I go and insert that Lead it will either throw an error ( duplicateCheck=1) of Update the previous one ( duplicateCheck=2), so I loose all the non-contact info of the first form!!  

Can I disable Duplicate Check altogether?  

Any workaround for this?

THANK YOU!