Good question gents!
I build almost all of my templates from scratch ... well, from the void, but sometimes I use other skinner's layers. As long as my template has at least one layer or one significant element from that layer from another artist I leave that skinner's name, and contribution if there is space, on my template. That template becomes "mine ... and another guy's".
I am using some ancient texture layers on many of my templates that other skinners did years ago. Except for one I found on an old "Jester's" piece I have no idea of their origin.