Java Application installed twice?

Hello,

iMac 21,5'' 2011 - OS X 10.6.8

I have some issue with missing plug-in in Mail application so was messing around with Java application. I have updates Java to the version I have already had installed so as the result I have now two lines of "Java for Mac OS X 10.6, update 5" in Installed Menu (System Preferences > Softawre Upgrade > Installed Software).

Two questions:
1. Shouldn't OS informed me that it is already there in the same version installed?
2. Is it OK I have it installed two times?
3. How can I remove one of Javas from this list?

PS.
When I search for Java application in the finder I can find only one.

Tnx!