Software update is offering me an update I've already installed

My Mac Mini came with Lion 10.7.3 and I immediatley used Software Update to boost it to 10.7.4; at that time i ignored the iTunes update and the others.

But Sotware Update is still offering the 10.7.4 update! Why? Should I update it again?? 😕

The "About this update" page for Lion 10.7.4 is

http://support.apple.com/kb/HT5167

///Polly