For starters, Copywrites apply to intellectual property, not products. The only protection GYB has is a trademark on the name "Senko" The only way to protect the bait itself is a patent, which I have yet to see a patent on the Senko (there isn't one )
The reason DoIt placed their logo in the mold was at the request of GYB, so the people buying the molds wouldn't try to fill his bags with knockoffs and sell them as real Senkos, which is exactly why they actually added GYB in the egg sack of their own.
edit: I missed in my other post that a common problem with the DoIt Senko mold is dents in the final baits, I believe they copied everything right down to the size of the gates used on GYB's production molds, which won't work for hand injection (a few people have fixed their molds by taking a file to the gates and opening them up a hair). You won't get that problem with the Bait Junky's molds.