No they only accept one return. You are still seeing the Accepted from the first one. You now have a problem. Go back and delete the second W2 and put your return back to the way it was the first time you filed. Then you can Amend it.
If the IRS accepts your return, then you have to wait until it has been fully processed and you have received your refund. THEN you can prepare an amended tax return 1040X and mail it in. You cannot e-file an amended return. Meanwhile, DO NOT change anything on your return until you start the amended return.
The 1040X form for 2018 hasn't been approved yet by IRS. Please, keep checking the following information on how to amend your return; it will be updated once the 2018 form is released:
https://ttlc.intuit.com/replies/3288565