Synchronicity in the creative arts is pretty weird. The independent invention of very similar things. Charles Fort, one of the masters of all things weird, even had a term for it: "steam engine time." Fort's notion was that when an era was ripe, it called forth certain creations multiple times, without coordination among mere humans.
I was reminded of this recently in a small way while watching the 1942 film TO BE OR NOT TO BE. In this film, Robert Stack plays a dashing Polish aviator named Lieut. Stanislav Sobinski.
What other fictional dashing Polish aviator premiered right at this time? None other than Blackhawk, who debuted in August of 1941.
Could it be a simple case of the Blackhawk comic influencing the scripter of To Be or Not to Be? Unlikely, given the short span between the debut of Blackhawk and the release of the Robert Stack film, which had to be in production for some time prior.
It's more likely that the plight of Poland under Hitler's invasion called forth the notion of a national hero. But why aviator? Just the romance of aerial combat, I suppose.
Here're pictures of Blackhawk and Stack in his role (leftmost figure, below) to compare. Stack is out of uniform in this shot, but when he's wearing his flying outfit, the resemblance to Blackhawk is uncanny.