When I load the low (no baking) the color goes through from the body to the shirt. But no problems with the edges not being welded, and it only happens in Painter's viewport.
As long as the issue doesn't occur in Iray, I'd say the issue is only due to the 3D view and not the textures, therefore the problem shouldn't appear in your rendering software.
Still, you can try to increase the shader quality to check if it persists.
Cyril Dellenbach (Micro) | QA Support Artist | Adobe