There is a possibility that even if the saddle is the same model, the manufacturer may have changed it in some small way. Alternately, your old saddle may have somehow molded itself to you even if not leather. Do you still have the old saddle or can you get it back?

a saddle? what are u riding a horse?

yes?

oh carry on then

For me, chafing is almost always a result of saddle tilt.