Cable service in Athens-Clarke County is not a granted monopoly. The Cable Ordinance (Chapter 6-16 in the Athens-Clarke County Code) states unequivocally that there is no such thing as an exclusive cable franchise for the community and state that franchises also allow for multiple cable providers. Athens-Clarke County and Georgia can and will review any cable company's local franchise applications to provide competition in the community.
In 2008, a statewide law in Georgia went into effect that allowed companies to apply - if they choose - for a statewide franchise agreement in lieu of multiple local ones. Only Charter and AT&T have applied for statewide video franchises and have notified the local government of intention to provide services in Athens-Clarke County. A full list is available at the Georgia Secretary of State's website.
Additionally, there is no requirement where services must be provided in a community, so it is entirely up to individual companies as to where they provide any services.
To date, no other cable companies have asked Athens-Clarke County for a franchise in Charter's service area, although satellite television providers also provide services without a franchise. The communities around the country that have multiple cable providers tend to be large cities and, even then, overlaps in services areas are rare to nonexistent.