It's not a fake. The people who collected it are quite poor and sell fossils from the area to commercial collectors. To make the pieces more attractive for the commercial trade (who cater to people who want 'pretty' fossils), they are sometimes doctored -- in this case, the broken tip of the snout was artificially lengthened with plaster.

That annoyed the scientists who first studied it, and so they named the species Irritator. Unfortunately, it's one of the hazards of dealing with commercially collected specimens, instead of ones collected under academic auspices.