It does have a similar seam, you are right. In fact, until more recent years, Vitro helmets were thought to have been made by Akro because the seams are so similar. This, however, is an Akro Tri-color. Very similar seams as you noticed. Something that helps often is that Akro seams normally are both curved like the one in question. Vitro seams often one is curved like that while the other is straight or wavy.