Blending modes and PNG export

Hey folks! 

Recently i've found something a little bit weird with illustrator blending modes. 

When i'm editing my file, the texture looks ok, but when I export, the texture is completely different than what I see inside Illustrator.

Is there a way to fix this? What am I doing wrong? 

This is very annoying because I need to double check the exported file to make sure the texture comports the way I want to.

I'll attach some print screens.