Fairly common modification
The widened hammer spur was done to make thumb cocking easier and more secure when shooting timed and rapid fire strings.
King's Gunworks in the Los Angeles area did a modification called the 'King Cock-eyed Hammer'. The hammer spur was build up on the left side (for a right handed shooter) and then shaped and checkered. I've not seen a symmetrical spur treatment, but I'm not the final authority.
It looks like a quality job. That was a premier target revolver in that day. They still shoot pretty well.
Don't change anything on that old beauty. If you want some other configuration, sell that one to a collector and buy a different one you like.