A funny twist to this.
When Slash (and GNR) was recording Appetite for Destruction, he wasn't using a Les Paul yet. He didn't like the sound of his guitar, so either the manager or producer borrowed a "Les Paul" from a local luthier. Turns out that this "LP" was a copy.
After GNR took off, Slash was able to buy that guitar and played it for a long time - still has it. Gibson actually borrowed the guitar to make the Gibson Les Paul, Slash Appetite for Destruction model.
In this case, Gibson took things in stride and realized that the copy helped their name.