A two-woman ticket makes sense
Senator Jon Tester (D-Montana) expressed regret after his blunder about conjecture regarding the possibility that Senator Elizabeth Warren (D-Massachusetts) might be considered for a vice president on a ticket with Hilary Clinton.
Tester said, "Well, I don't know. Is the country ready for two women?"
Tester should know better than that, and based on his apologetic tone afterwards, he does know better. There might still be some cases of arrested development who think women are unsuited for any endeavor other than making babies and baking cookies, but such types would not vote for a woman for president regardless of the gender of the other person on the ticket.
Warren would actually provide balance on the ticket, a gesture of respect to the progressives who rallied behind Bernie Sanders.
And what's with Trump's nickname of "Pocahontas" for Warren, a reference to her Native American heritage (which is unconfirmed and remote, if it exists). Most of Trump's nicknames for political opponents are pejorative, but Pocahontas was a sympathetic historical figure. Perhaps Trump believes that characterizing someone as a Native American and female is in itself a double pejorative.
There are not a lot of famous Native Americans to choose from.
Trump may not be able to pronounce "Sacagawea" and Trump may not be aware of her existence, since Sacagawea was never the subject of a Disney animated movie.