There was good reason.

The world knows there was but one man on the planet at the time who was competent--not a dozen, and not two.

A long time ago the dwellers in a far country used now and then to find a procession of prodigious footprints stretching across the plain--footprints that were three miles apart, each footprint a third of a mile long and a furlong deep, and with forests and villages mashed to mush in it.

Was there any doubt as to who had made that mighty trail?
Were there a dozen claimants?
Were there two?
No--the people knew who it was that had been along there: there was only one Hercules.
There has been only one Shakespeare.

There couldn't be two; certainly there couldn't be two at the same time.