After you file

Hello, I am also having this same issue as everyone here is having. 
I would like to use TaxAct but am concerned about dual filing and running in to issues with the IRS. How do you cancel the TT submission?  Or will the IRS just reject it bc the TaxAct is already accepted? 
I have seen several people state that they received a couple of hundred dollars more of a refund from TaxAct.  
This makes the concern with paying for tax service a second time less of a concern.