^those jeans marc is wearing might be the dark unders, which is basically just a darker version of umc with pretty much the same details. they definitely aren't the used, as those are lighter. the used are the same as clawmarks, fyi.
Dark unders, are they released from season to season like the umc's, or are they more limited?
i think they only did them once. besides the raws, pretty much only the used/clawmark jeans and the umc is done every season. there have been several pairs that were remade a few times, but a lot of stuff is only done one time. and even the stuff that is re-released each season or even occassionally tends to be changed a bit from run to run.