There is a regression with 7u21 and 7u40b26 (on Windows 7 with 32 bit).
If the host name of the jnlp codebase is written in uppercase (see the attached jnlp file) then the security box appear 2 times. Also the selecting of ever accepting the certificate has no effect. The 2 security boxes occur on every start. If the host name in lower letter written then all is working.
The only effect is that you can delete it 2 times in the system control. This is another bad things.