SF movie, hopefully not 2 movies

[matiren]

So this is not a blockbuster, no feature of well known actors, I’m afraid, too.
And I’m not entirely sure if it’s one or two movies, I remember two scenes, might be from different films, if so I’m willing to watch both.

First scene: post-apocalyptic scenario, abandoned building, people wearing old dirty clothes, hiding. There are troops that are hunting for them. Those poor people are hiding something - they’re gathering some ‘parts’ of some devices, making plans. These device - when build - will be used to fight in the future action.

Second scene - this is a spoiler, actually. In this movie (this might be scene from another movie, I don’t remember) there are two groups of warriors, soldiers. The first one we are looking wear some special helmets - they are told the helmets are protecting their brains from ‘aliens’. But - we know it at the end, there are no aliens at all - the helmets make people think their enemies are aliens, but in fact they are humans, too. When they take off helmets - they see that are fighting with other people, too.

The movie(s) is from 2010-2020 probably. Thank you and sorry for my English.

[OmegaMan]

This could be the whole thing, but it is the solution to part 2, at least.
British TV Series Black Mirror Series 3, Episode 5 - Men Against Fire.
The episode follows Stripe (Malachi_Kirby), a soldier who hunts humanoid mutants known as “roaches”. After a malfunctioning of his MASS, a neural implant, he discovers that these “roaches” are ordinary human beings.