When you transmit your return, it goes to a "data warehouse" (a server someplace) where it waits for the IRS to download it. This should happen in less than 24 hours. If there is a delay, it is usually because of the IRS, but I am not convinced that every delay is due to the IRS, there seems to be some delays that might be due to Turbotax, but I can't prove that and have no official information either way.
If you e-filed a second return using another service, it would also go to a data warehouse. (There might be only one server, or each company might have their own, I don't even know that.) Whichever return is downloaded first by the IRS will be processed, the second one will be rejected as a duplicate.
So you could (probably) e-file a return with a second company and see what happens. There's no way to know which return the IRS will ultimately take first. However, if you paid to use Turbotax, and it was the Turbotax return that was taken second and rejected, you probably would not be given a refund. (You would have to call customer support and make a case.)
