That build was said to fix no known issues or new features, but Apple has asked developers to focus their testing on AirPlay, AirPort, Game Center, Graphics Drivers and Safari.
It’s not clear why Apple has seeded a second update so quickly, as people familiar with the two builds say that developers are being asked to focus on the same area. The release notes are said to be identical. As far as anybody seems to be able to tell they are the same, but Apple must have made some change.
There’s speculation that the first test build had a security flaw, or some oversight. The build is in Beta so Apple will clearly be introducing new features, fixes, and enhancements as it goes.
Apple seeds software builds early to registered developers so they can test their software on upcoming versions of Apple products. Apple recently introduced the iOS 6.1 Beta 4 build to the Apple Developer Connection.
These beta updates have been made available to developers as the public have been given an iOS 6.0.2 update for iPhone and iPad mini that is said to fix a WiFi bug.
Also this week, Apple posted updates to the WiFi and EFI firmware for almost all of the Macs it released in 2012.