A lot of them come that way, also those little ones at the supermarkets. Sometime check a Christmas poinsettia -- they too are often done that way. Yes you can divide them; but be careful, they usually don't have much root structure. Remove from pot, soak in wanter, gently divide under water. Repot quickly.

They are really just blooming branches that have been rooted.

They put more than one in a pot because it looks fuller, and they can sell more plants than waiting for the cuttings to mature. If you buy a mini from a rose vendor, sometimes you'll get more than one cutting in the pot, but more often you'll get a larger cutting that has more roots.

See the link below for more help.

Here is a link that might be useful: How to save a potted gift rose