I caught the same 6 pounder twice, but I knew that because it had two spines on its top fin where there should only have been one.
I had been cutting the webbing between the first two spines on the bass's dorsal fin, but that webbing grows back after a while. I found this out when I caught little bass with a big red sore from where my jig hook stuck him the first time and the webbing had grown back on the fish. Call your DNR and ask about tags for fish. That's about all I can think of...