It should have the stamp, though it may have worn away or been cleaned off. I'm not aware of any Heydler NL baseballs that don't bear his stamp. Another thing to look for are minor league president stamps. Those are collectible as well but they don't carry the weight that an NL or AL president stamp will. The minor league balls of the teens and twenties have all the same markings as the major league counterparts with the exception of the president stamp. Usually those leagues are indicated under the presidents signature.
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