Yes! Numerous free slaves actually became slave owners themselves. For example, William Ellison a former slave owned 60 slaves, and supported the confederacy. 'Mulattos', a person of color who was fair-skinned enough to pass for white often did so. Several free-slaves accumulated enough wealth to actually own plantations. You may also be interested in this link. The history of slavery in the United States is by no means my area of expertise.