First of all: I have 2 monitors and my friend aswell.
2 Problems:
- When im starting DayZ it starts in the bottom right corner of my screen and covers about 2/3 of the screen, which is not that bad, because i just have to minimize it and max it again
- When my friends starts DayZ its always in the wrong resolution and he has to set the right resolution and restart it once, then it works fine