Apple has today seeded the second version of macOS Sierra Gold Master. This was likely released to developers for a second time due to a large issue found. What users will see what it launches the 20th will now be this version, rather than the first version. Unless there is another update to the Gold Master, this is what the public is going to see.
To get the latest version, developers can testers can go to the Mac App Store and find it under the updates page. If you haven’t started testing it yet, you can download the installer from the Apple Developer center downloads page.