although a large rhizome can have several growing points, but it still only counts as "one plant" because there is one rhizome..
so if you have more than one growing point, you either have:
a. one plant with multiple growing points.
b. multiple plants, with separate rhizomes. (probably more likely in your case)
but IMO, you really shouldnt even worry about it right now..
your plant (or plants) should not be disturbed right now..
you should keep growing it as-is, dont un-pot or re-pot it just to see how many plants there are..its unimportant right now, and it will unnecessarily stress the plant.
just wait, keep growing it as-is this growing season.
then put the plant through dormancy this winter..
THEN, early next spring, right before the plant is going to come out of dormancy..
late February or early March..then take the plant out of the pot to see if its multiple plants..
if it is, divide up the plants into individual pots.