Experts ? plz help !! how to install get both 4.1 and 4.2 camera ?

okay, i just tied 4.2 camera .. it worked properly except 2 things..
i wasn't able to get pinch to zoom working and touch focus wasn't working aswell..
after facing this problem i switched back to the default camera.

so, i have 4.2 camera apk/zip file .. and i want to install 4.2 camera without removing 4.1 stock / default camara..

how shall i do it ?
plz help me.

You cannot. You cannot have 2 of the same apps installed in Android, even though one is a different version.