There are records available on free Negroes in Mecklenburg at the Library of VA for the years 1827, 1831, 1831 and 1838 to 1839, and 1842. Not sure if they have been microfilmed or if it is still the original document you will have to call and check.
It is also identified as being 5 items, so not sure if these are actually list for many people or just copies of individual free papers...however they do identify it as a register.
Selma