Well mine says its an a501 in the device information section, but it was sold as an a500 and it is recognized as an a500 everywhere else, and my device doesn't see an update.
Not only that but there seems to be different build numbers installed out of the box. Mine is 1.104.02. I have also seen on XDA people having 1.126.03, and 1.016.04 and 1.105.01. Some versions end in GEN1 and others in GEN3.