Looking for Nomex pants the other day I found these:
For one they claim to have a reinforced knee, which I hope means it's actually a double knee unlike Vertx's faux-double knee. For two they have an interesting double crotch, this unfortunately replaces the wonderful crotch gusset but it does reinforce what I am starting to think is one of the major week points of many pants. Less knee articulation and the typical wildland fire feature of velcro leg closures as well as a more typical slash pocket round out the differences.
Why was I looking at Nomex pants? I have heard it suggested (in a textiles textbook) that nomex is slightly stronger then normal nylon (which is much stronger then cotton duck, denim or canvas) and I was wondering if Nomex pants might provide a more durable work pant if you could find a good deal on them.
Double seats are fairly common (at least on military pants) but double crotches much less so, I will be keeping an eye out for more now.