The dimension drawing listed on the product page shows the dimensions that the bracket is specified to. In this case, the center-to-center distance between mounting holes is supposed to be 6.35mm (0.25″). I measured a couple 25D motor brackets here, and unfortunately, it looks like the hole spacing is not correct. My measurements were similar to yours (about 6.2mm between holes).
Thank you for bringing this to our attention. We are now looking into the problem, and I will post an update when we get more information.