#1 Goblin Mine in Campaign mode?

I was checking out my stats for my profile to see how many eliminations I've got with different weapons. So as I went through the list, I noticed that every weapon was there, including the Goblin Mine. Now, in the booklet, it says it's only in MP, but if that status is only for campaign mode, then why the hell would it be listed there? It could be just a simple mistake, but most of us already know that the Golden Gun can be found in the Hong Kong stage in campaign mode, and in the instruction booklet it says it is only in MP. So it is possible that this weapon is indeed in campaign mode as well, but if it was, you would think it would be found by now.