What makes you think that because it is similar so Vietnam copy? When did China make those drones? When did Vietnam made those drones? Ask yourself that questions. As I said the tech already existed from westerns, you Chinese invent shiit.
Look at these pictures.
Do they look like the Chinese ones? Go type unmanned drones on google. Funny these Chinese, king copycat accused other copy from them. Should I laugh or cry.
The drone that make this guy known are not those drones above but his recent one.