See attachment.

1. Intall java 6u10
2. Open java control panel, go to java tab
3. Under Java Applet runtime settings, click on the view button.
4. Click on the find button and select the same jre which is already listed in the table ( eg. c:\program files\java\jre6 for windows)
5. Click next -> next and then Finish button in JRE finder window

If you see, the same JRE is getting listed twice in the table, the bug is reproduced. 

How it does not impact much : 
Though it get listed in the table, when OK is clicked, it finds out intelligently that there are two entries and it removes one. When you open next time by clicking the view button, you can see there is only one entry listed.

How it impacts :
Set some Java runtime arguments for the first entry. When the second entry is added and clicked OK, it makes the latest one (second entry) as the valid one and thus loosing the runtime arguments. 

What is Expected : 
When the Finish button is cliked on the JRE finder window, it should popup a message saying there is already one entry existing which points to the same location. There should not be a redundant entry, rather it should highlight the same entry in the table on click of Finish button.