Tis alright Matt. No need for explanations. Just wanted to put out that info to you.
I know that in the Windows area i have created a bunch of topics about OEM vs Retail and give full details of such things. But the terms of the EULA and TOS are always questionable cause it cant cover every circumstance.
To be honest if it is the same make and model, there shouldnt be any need to call Microsoft. But if you do just flat out tell them that the mobo was defective and replaced. They will activate it for you.