I agree with the others, several years ago I bought a Dureme on sale on-line and was bummed to get a much heavier stiffer tire in the mail, it was labeled Tandem Ready.
I have an old 2012 copy of their catalog on my hard drive. I attached a screen shot from page 36, that suggests a Tandem (double carcass) version, a wired bead version and the standard folding bead version.
All three versions are different weight.