Background image size on multiple monitors is incorrect

[vantu5z]

I have 2 monitors connected with resolution 1366x768 (main) and 1280x1024 (second monitor).
On main monitor background croped from right side (86px) and repeated.
I try play with background-image-size in config, but have no success.

versions:
lightdm - 1.30.0
greeter - last git version.

[vantu5z]

Found, that if we have cloned monitors with different resolution backgrounds created for all monitors but shown on primary.