I'm using a 3x3 devourer mobile grid to make explosions explode in a straight line from a unit. So for example, I make explosions going right from a unit, and it works good for one player. But if another player makes an explosion going left on the same line, they collide and one line ends up going 3 lines up or down, because the triggers make them both make 9 devourers on the same place, and it screws it up. Is there any way to fix this?

You could make a delay inbetween the explosions.
While a unit is dying it still exists for SC for a short moment, so you can't create a unit there.

Use remove unit (not kill) wherever you can.

Separate the actions that create the wriath(or whatever unit you're using for the explosion) into a second trigger immediately following the first, and add an extra condition:

Force 1(or whatever players can have the spell) brings exactly 0 explosion_unit to explosion_location.

That way it will only create the explosion once.

The explosion itself would displace the mobile grid as its being made, you wouldn't even get the location to detect the vacancy there over there if it is there, rendering it useless.

Alternate making the explosions over each loop? Do you need it every loop?

I'm not sure if anyone said this but: alternate the mobile grids.
So player 1 would have it mobile grid spawn at a certain moment, than a counter is set so that it must wait until next player's grid has spawned.

you could make explosions created for two differing computers and when they meet using semi complex though easy if you sit and do it on paper designs you could make it so each explosion when in proximity to another's spawn cancels out that portion of the explosion and they merge so when 1-3 explosions of comp1 are in range of the explosions of comp2, remove the sides, 4-9 will req removal of all or atleast all excluding middle to function properly, not the best idea when i think about it but it'd still have some use...