if you currently have 2 receptacles on the same circuit you're gonna have 1 hot and 1 return going to the first receptacle and out of that receptacle to the second. Since the two recptacles share a homerun adding a second circuit without isolating the second receptacle will turn the circuit into a 2 pole 30a circuit. Do you have a crawl space or basement? Without having access from above out below getting a new circuit is gonna involve a lot of holes in your drywall, especially if your joists are perpendicular to the direction you are feeding from.
