It appears that GPD did some improvements and came our with a V2. It has a different eMMC, better fitting buttons and a slightly different case - matte finish.
However, reports from HotUkDeals suggests some people have been unlucky in getting a chimera, which is part old and part new version.
The old model's eMMC is supposedly slightly faster but it shouldn't make a difference in the real world.
So if you're buying one, it's worth checking which version you're getting, especially if buying used.