The H-bar clamp could have been changed or Yes, someone could have replaced the foil Sting-ray decal.
After my post I went and looked very closely and compared the two mirrors, observing the swivel part that attaches to the mirror but it's a very close replication. Very hard to tell any difference between them. They produced these for many years, so there is going to be some variations in the originals too.
As for the paper sticker, the early Schwinn Sting-ray Racing Mirror had a bend in the attachment arm and the Sting-ray was on a white paper background with Red text.
See attached photo, from a 1970 Schwinn Catalog:
*Notice placement of decal. I've only ever see one of this style.
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