This is a 1960s YIP flyer secretly kept on file by the FBI of the time (recently released under the Freedom of Information Act):
Here's a side-by-side:
BoingBoing notes, "Yahoo's was designed by Organic, Inc. in 1995, and refined a few years later to use the Able typeface (also used in the Harry Potter franchise) Able, from foundry T26. The typeface was designed by Marcus Burlile, who was not born until the 1970s."
Now THERE's a conspiracy theory worth looking into, G-men...