Finger, Swan and Kaye have a fairly simple tale in World’s Finest 74 (Jan/Feb 55), but it concludes with a visual that would endure for decades.
An alien shapeshifter comes to Earth, encountering first Batman, and then Superman. The heroes aren’t sure what to make of the creature at first.
Eventually they determine that the being is simply playing, having fun. It adopts the forms of Batman and Superman because it admires them.
They get the creature to head back home. In the final panel, we see it adopt a body that is split between the two heroes. It would be a number of years before this visual returned, as the Composite Superman. All later version of this would have the chest symbol split as well, rather than showing both, as this one does.