If I had to venture a guess, I would say that it is original.
The stamping looks correct.
The detail on the reverse is good, not bubbled or distorted.
The solder looks correct.
The patina looks good for it's age.
I would say if it looks like a duck, walks like a duck, and sounds like a duck, it must be a duck.
It is a stamped piece, if you look at the long ray at the 12:00 o'clock position there is a little damage or flaw. This would not happen with a casting.