You ever notice that the 5 punched depressions; 2 rear by springs and 3 forward of the seat post clamp are irregular patterns. A large and small set of triangles irregularly positioned And they were stamped/punched in after the paint. The center of each hole has the tip scratching off the paint.
That means it's very likely; after the seat was completely assembled. that set of depressions was hand punched, or hand held, positioned with a punch bandit, [one pull punch]. .
No two pans, microscopically, would be alike. That, because of those stamped depressions,, it's easy to set another besides it and tell the difference between them, And,,, copies ain't. [yet?]