'Your account already has a valid iOS distribution certificate'. I get this error every time I try to upload my archive. I don't have two dev accounts, nor did I use another mac before. Please help
Your account already has a valid certificate
This dialog appears if the certificate already exists in Member Center.
Typically, this happens when you move from one Mac to another. If possible, export your certificates as a developer profile file on the other Mac, and then import them on your new Mac.
Have a look into Troubleshooting section of App Distribution Guide. It is described there how to solve this error.