So ive been trying to do some both eyes open shooting for a few months now to combat eye fatigue of closin my left eye.

The issue i run into is that when i have both open and using my iron sights if i focus on the target i get two buis. If i focus on my front post i get two targets, is there any way to avoid seinf double targets? or should i just learn which to shoot and ignore the other

Ignore the other. I'm right eye dominant, I shoot the one on the right.

I shoot NRA High Power and CMP Service Rifle competitions.  Iron sights at 200, 300 and 600 yards.  

You can take your shooting glasses and put a piece of Scotch tape on the left lens right in front of your eye.  This way you can keep both eyes open but the left one doesn't really see anything.  I shot this way for about a year and then got a shooting cap that has a flap that hangs down in front of your non-dominant eye; basically doing the same thing.

Also, you should be focusing on the front sight and not the target.

Good luck.