That number is indeed the MAC address. Have you checked this link? http://www.codeproject.com/Articles/850627/GalileoplusWindows-IoT-Part-Getting-started-with.
I would suggest you to contact the Microsoft team in charge of the Windows IoT image, we support the Yocto image, so in this case I believe they will be able to provide a more accurate answer to your question. Here's the link to their community, Community – Windows app development.