I dunno, Gus. I took the shot and lighened it up a bit. It sure looks like it could be a "factory" job. The braces and ferrules all match and I don't see any outlines where a brace might be removed:
Hello. I have a York Master DB Euphonium which I purchased new in 1965. It has a 3 & 1 valve configuration. It was made in Germany by Schrieber.Both bells rotate and face forward.