Orders Table and Duplicate Records

We are using the Marketo order table to track the information about the customers who buy our product.  This information is then used for our renewal campaign.  The problem comes when a user places multiple orders throughout the year.  Let's say it's a business and they buy 5 licenses, then another 10 licenses, then another 5, all on different days etc.  When we load the initial order, it has all of the order information such as the date, the amount, which product was purchased and at the time that we import them, we attached a unique coupon code for their renewal, which may be 12, 24 or 36 months away.  But when we load that second order, it will overwrite all of the information about that first order, which means a renewal notice won't go out for that initial order - it will only go out for the very last order that they placed.

Is there any way we can keep duplicates in our order table so that subsequent orders will be treated as unique?  Especially with businesses, it tends to be the same person placing the order each time which means the same email address is used.