They are clumpers, slow to expand and are sterile, so if you want more you will have to divide them. Calamagrostis x acutiflora is a deciduous grass - it dies back to the roots in winter, leaving the straw colored foliage in place for winter interest. These should be cut back in early spring before new growth really starts to expand. 2' is still pretty tall - I'd cut them back to 4-6". You can divide them at the same time you cut them back if you wish.

They will increase in circumference, with new growth shooting out around the outside.
You can leave them alone (i.e., not divide) if they're healthy.
If the insides start to look poorly, dig 'em up and divide in late Winter or early Spring.
Cut down to 6 inches in early Spring or when you see new growth starting.
Your neighbor might have cut to 2 feet to provide some protection from cold...maybe.