There are times where an update is broken, and M$ re-releases it with the same KB to fix the issue, while rare, it does happen... Below are typical scenarios...
1: Broken update is released, not horribly broken, but enough to cause issues. Microsoft leaves it, and re-releases the same update with a few tweaks, everyone downloads and installs the latest version.
2: Broken update is released, horribly broken and causing issues. Microsoft pulls the update immediately and re-releases the same update later after other updates are deployed, in hopes of fixing the issues.
3: Broken update is released, horribly broken, and is on too much of the customer base to pull the update. Microsoft starts working on one or more updates to fix this update.
There are a few updates that fall into that #2 category... Remember my GPU errors where I had to always reload the driver at bootup to play ANY game? Yeup, it was a broken update that Microsoft deployed 4 different times!