I accidentally filed my federal 2023 tax return twice - once with freefile fillable forms and once with Turbotax...what should i do?

It is impossible to e-file two returns.  One of them will be rejected--we just do not know which one it will be.   The IRS will not accept two tax returns that are using the same SSN.   Watch your emails for the messages abu the returns you e-filed.

When you e-file your federal return  using TurboTax you will receive two emails from TurboTax.  The first one will say that your return was submitted.  The second email will tell you if your federal return was accepted or rejected.  If you e-filed a state return, there will be a third email to tell you if the state accepted or rejected your state return.