My gpu is : Sapphire Radeon R7 240 2gb, I tried with r_fullscreen_forcestretch, didn't work and I have only one monitor.
But I think the problem is that my reflex isn't loading the "Courier" font (Which is the default console font I think), because I deleted it from the fonts folder months ago.
Now I reinstalled it, but it doesn't work anyway.
If you look closer, you notice that it isn't a resized font, it is completely another font and I think it is causing this glitch.
Maybe I have to make reflex load the font somehow...