^ True, however, I have seen different motherboards shipped with different BIOSes. Dell does this on their servers. Same motherboard, but cheaper models have different things disabled.
HP could very well do this. They would make one board and use it on a range of systems, making you buy the more expensive model to get more ram, just in the same way GPU makers make one die, and sell the half broken GPUs as lesser models.
I suggested the check so he could see for sure, to save time, frustration, money(?). It's an easy check too. And as I mentioned, it's quite likely it will show 2GB, but I'd check to be sure.