Wait and see how the small one grows. I've had really small ones that did as well or better than big, beautiful rhizomes. That's especially true if they come from an area of low rainfall. Rhizomes grown here tend to look starved compared to many that come via orders from other places, but I'm sure it's due to the dry growing conditions and green dormancy in the hot summer months. They still bloom and increase when spring arrives. If they look healthy otherwise and are not obviously immature rhizomes, small size doesn't bother me.
Texas Zone 7b, USA