How can I make a double button door? By that, I mean that two people have to switch the same button at the same time to open a door for a short time, and then these door would close up behind them. Please explain how to do this or link a tutorial.
AND gate into a pulse extender. The time provided by the buttons themselves (1s for stone button, 1.5 for wooden) should provide enough time so that they "must be pressed simultaneously" is decently tight but doable. The pulse extender (using 2 comparators) will provide enough time to pass through the door and close it afterwards.
This version of the contraption will work with any edition of Minecraft that supports these components (so pretty much every except for the most stripped-down ones like the 4k, Raspberry Pi, or JE older than 1.5).
Cant Redstone signal pass-through blocks using a repeater? So have one button power a sticky piston with a Redstone block on it to power the Redstone line, then where the second button is, have a repeater, then a gap, the more dust line, and where the gap is, have the second button power a sticky piston to push a solid block, such as stone, to the spot right in between the repeater and dust line.