Even the single seam CACs, if they are machine made, they have 2 seams. It's impossible to have a one seam machine made marble except for the very first gob of glass that comes out when the tank is opened, and that is garbage because the rollers are cold, nothing is working yet. You might only see one seam, but there are two. The marble before it was cut off, there's the one seam, and the cut where the marble in question was made, that's the other. This has both seams at the same place because the ingot folded on itself.