But there is something else at play here. One of these Gravemakers appears to be on defense while the other on offense. I can tell which one by looking at the elemental links in the images. Defense gets an additional 20% boost over offense. In this case, you can backcalculate the base stat and get the following:
508/1.26/1.20 = 336
424/1.24 = 342
Now you have a difference of 6 in the base stat which is reasonable. I believe you are seeing the 20% defense bonus.
