After you file

I did a 2019 federal tax form well a friend did it but I didn’t realize she actually sent it then I did on my own a simple stimulus form well I don’t know it says stimulus was accepted what happened to the 1040 form that went through? How will they know I want a stimulus now that both forms went through ? Also I tried the form on irs.gov 

for non tax filers. It said the social security number was already used and already filed. And wouldn’t accept form why? I hope this isn’t messed up I get ssi