You could do as following:
Make a second sprite for the hero, name it "HeroIDLE" or something, give it the 2 IDLE sprites as animation, right on frame 0 and left on frame 1 with 0 Speed so the sprite won't play an animation, make it invisible and make an event as folloing:
"HeroIDLE" set position
Tis way the idle hero will always be at the same possition as the hero sprite
Now the magic trick: When you need the hero to become IDLE toggle it visibility to "Invisible" and HeroIDLE visibility to "True" and set HeroIDLE on frame o or fram 1 depending on wich direction the "Hero" was facin before turning invisible!!
Hope youu understand me =)