Peel and stick vinyl planks over vinyl
I am not a fan of putting down vinyl over vinyl.  Instead of leveling, I would strongly encourage you to remove the old floor, clean the underlying surface, possibly lay down a new sublayer of hardboard (basically pressed cardboard) and then apply your tile to that.

Vinyl over vinyl as stated by Damon will result in poor adhesion and if you're going to the trouble of leveling it, you may as well remove it and clean it up.  Building up the floor again and again will also result in uneven step differences between rooms.