Yes, they can be quite successfuly divided, although growing in dense clumps or colonies is their typical growth habit. Generally, right after bloom season or early fall is the recommended time for this activity.

Here is a link that might be useful: propagating/dividing hellebores

Jeff are yours thick looking becasue the baby plants have grown up around the mother and are competing for space or because the mature plants are too close?
It is good for the big plants to have around 18" between them. If the clumps are not flowering this year you can dig them up and separate them now if you want.
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In the above photo there are lots of plants but they are about 18" apart. In the spring I try to pull out all the babies so that I don't get big clumps competing for space. Friends like to get free plants.
Mary/Gainesville, GA