Adjusting wallpapers on dual monitor configuration easy

I have TFT monitor with 1280x1024 resolution and TV connected in nvidia twin view configuration with TV's resolution of 800x600. Whenever I want to set up a desktop wallpaper on Gnome, I must adjust it, because Gnome "sees" my desktop as one large 2080x1024 desktop. So, I must manually open wallpaper in Gimp and create another picture that contains two wallpaper next to each other, one with 1280x1024 dimension, and another one, with 800x600 dimensions right of the first one. So, I decided that that's enough. So I utilized imagemagick to accomplish this and put convinient function in my .bashrc file. Here it is:

make_wallpaper(){
    convert -background white "$1" -resize 1280x1024 \( "$1" -resize 800x600 \) +append "$2";
}

Of course, background color isn't neccesary since it is not visible, I just put it as a reminder. All I have to do now is to call:

make_wallpaper original.png my.png

Sweet, ain't it;)