This has been polished at some time in its life, and the cylinder scene, the lightest marking on these guns, has been polished off, but the other wording on the cylinder is still there.
Look at the first photo you posted. The frame surface should be absolutely flat. But you can see some "dishing" at the screw holes - this means they were polished with the screws taken out, and the edges of the metal were rounded downward (making a ring of lower metal around the screw hole, like a "dish" and so called "dishing"
You can see this same rounded edge of the metal of the frame where it meets the wood.
Colt didn't make them this way
But a less than professional polisher will leave those rounded edges, and your Colt shows this....and that's where the Naval Battle cylinder scene disappeared to - the polishing wheel of a fellow who thought he would clean up this old timer a bit.