Walk Property Discrepancy - Two puppets at the same size and same body speed move at different speedsre

I have two backgrounds that I've made into puppets in order to walk in the opposite direction as my character, they are the exact same size, however they move at different speeds when they share the same walk properties. Does anyone know what make for the speed at which a puppet moves? I was under the impression that it was based on size, however that isn't the case based on my project. Any help would be greatly appreciated.