High is printed incorrectly

[miiu]

I am just getting started with my prusa i3 /marlin. I have problems with high (z). My printer is making every time printed parts twice as high as they should be. Testcube was 2*2*4, every objects I make like 4mm are truly printed 8mm ect. I have edit layer high but it makes object smoothier but same still same size. Is there any easy way out of this problem? I have already updated firmware because of this issue. I am using cura 15.04.3 and repetier host v2.0.5. Thank you so much!