I created my return and efiled today. I created a second return to calc 2019 estimated tax pmts but did nothing with this second return. Both now say they are efiled.Why?

Not sure what you mean by "second return" but you cannot efile a return twice.  And you use the one account to complete the estimates either BEFORE you file  or AFTER the return has been accepted. You didn't post what program you are even using ... online or downloaded .... so here is some general info :

Can TurboTax calculate next year's federal estimated taxes?

https://ttlc.intuit.com/replies/4242911

Can TurboTax calculate the estimated payments for next year's state taxes?

https://ttlc.intuit.com/replies/3301735