No one has a patent on the hexagon, but many Chinese pens are copies of those from other "real" manufacturers down to copying the feed and nib designs, cartridges, etc. There is also the widespread phenomenon of knockoff Lamy styled pens which have stolen the rather distinctive Lamy visual design while also often remaining maddeningly incompatible with genuine Lamy nibs and cartridges. It's impossible to scroll through any list of Chinese fountain pens without passing by several Lami Safari clones.
Quite a few Majohn/Moonman pens are explicit rip-offs of Montblanc designs, and they've even knocked off the Ohto Tasche with their N1. The Jinhao "75" is a rip-off of the Parker Sonnet. Tons of pens are rip-offs of the Parker 51, typically its revived incarnation, including like half of Jinhao's entire product line. Etc., etc. It's not just the retractables.

