Helmets indeed has unique styles but there were some Helmet that are popular that used in Movies, Sports, and Video Games. Because of these popularity, some Industries got an idea to get the similar design of the helmet, well it is not 100% to be a copy-cat or duplicate but we can say the it looks like the design. I think they got this idea to capture the attention of the fans to buy this product but still it is good marketing strategy.
In the First Line, it shows the Bell Rouge Helmet a half-helmet type that looks like “Dart Vader” in Starwars Movie. The Second one is the Nolan N44 Trilogy Modular Helmet that in the picture above it looks like a helmet of “American Football” Sports. Lastly, the Arai XD4 Motocross Helmet that has the similarity look of “Master Chief” in HALO game.