Yep, the one tool does both in one shot. From what I've found, I'm more surprised by the burrs that come out of Lake City brass than the occasional slightly small flash hole. But, the ones with slightly small flash holes usually are the ones with huge burrs inside.
With the Lyman tool, you adjust the cone part to control how much brass the flash hole tool trims, and it deburrs the inside of the case and uniforms the flash hole in one shot. Really worth a try, especially if you have an automated cartridge prep station like the RCBS, Hornady, etc.
John