Around here there are a lot of people who down server admins who use tons of custom content. As a TTT player I enjoy going on a server that has a new weapon that I have never seen/used before. It gives me a reason to want to go to their server and try out the weapon and see how it is. On the NxS server I really liked the change in the vgui, getting to see something new rather than the default TTT vgui was a treat and may in fact even be an incentive to come to their server.
I have the same problem. I even tried to copy the C4 code and just make a second c4 called c42. With the same code, other than the name of the weapon, I got the same error.