Washington–Franklin Issues

The Washington–Franklin Issues are a series of definitive U.S. Postage stamps depicting George Washington and Benjamin Franklin, issued by the U.S. Post Office between 1908 and 1922. The distinctive feature of this issue is that it employs only two engraved heads set in ovals—Washington and Franklin in full profile—and replicates one or another of these portraits on every stamp denomination in the series.

Source: Wikipedia — Washington–Franklin Issues (CC BY-SA 4.0)