Multiple "Authentication required" pop-ups while running restricted basic auth JNLP application

Mutliple "Authentication required" pop-ups has been noticed while running the JNLP application having restricted access using HTTP basic authentication scheme. This is regression in behavior as compare to 6u17. With 6u17 and earlier releases "Authentication required" pop-up is seen only once

Steps to reproduce:
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1) Install 6u18-b07
2) Try to run following JNLP application
javaws http://mossad.sfbay.sun.com:8080/basicAuth/tests/BAT.jnlp
3) "Authentication required" popup from Java is going to be there asking for username and password.
Enter info as follows:
User: jituB
pass: jitu20
Click "OK"

After a while if you notice the same "Authentication required" popup again then bug is reproduced
Enter the same info as above and click OK, application should run successfully