Software Competitive MIR Question

[Satori]

This is my first post here, and I hope someone can help me with this: I just purchased software offering a mail-in rebate to individuals who own a licensed version of certain competitive software. The rebate request form asks for the serial number of the competitive software -- does anyone know if they check that the software is registered in the name of the person requesting the rebate? I purchased the competitive software from half.com earlier this year, and while it came with the box and manual, it had already been registered in the original owner's name who'd used it for a couple of weeks before listing it on half.com. So, while I have the serial number, the software isn't registered in my name, and I wonder if that means that I won't qualify for the rebate?
Any info/suggestions much appreciated!