You should always use a plastic strapping seal that is the same size (width) of the poly strapping.  Using a plastic strapping seal that is wider than the plastic strapping width could result in a 75% joint efficiency decrease.  For instance,  If you used  1/2″ poly strapping with a 5/8″ plastic strapping seal  there would be a 1/16″ gap on each side of the seal.   Less plastic strapping to crimp causes the joint deficiency.  The Poly Strapping in the seal is most likely to slip thus making your package not secure.