The only way you're going to get rid of the seam is to make sure the scans line up properly and then edit your verticies so that they make the textures meet at the proper points. You'll want to be sure that the textures themselves have the same tones and patterns on both sides- it looks like the back of the hand is a lot paler than the palm, so try fixing it in photoshop or rescan it first. Unless someone out there knows a better way, that is
