When Alan turns into his Heatblast persona, he has the Plumber icon on his chest. Ben's Heatblast transformation has the icon on his chest because the Omnitrix/Ultrimatrix shares the icon as well. It would seem Alan shouldn't have the icon on his chest, since the transformation is a natural part of who he is, but his Plumber badge is alien technology that sticks around (literally on his chest) when he changes.