I see it mainly in Fantasy Books.
One Brother is the good one, he is manly, strong, don’t care about riches, and have a good heart. He will be the protagonist or the protagonist friend.
The other one is the Bad Brother, he have a more weak body, have femine traits, always using fancy clothes and jewels, is less loved by others, and he is jealous. He will be the antagonist.
In a arc of >!Ranger!< this trope is reverse, which was a breath of air.
Not just a single modern handgun.
The good guys are all elves and fairies and whatever fairytale creatures, using magic and swords and spears, while the bad guys are all orcs and robots and whatever abominations using tanks and rifles and projecting Nazi propaganda and war imagery TO THE SKY to scare the good guys.
Oh, almost forgot: one of the aliases of the evil twin is just “the führer”, and his throneroom is in the shape of a swastika, with the throne in the middle. The film isn’t too subtle.