Dhilip,
The first question is strange, usually admin ui does not co-relate to policy store connection account.
Those account information is stored in registry file, not in policy store at all.
Maybe you have report server or audit server connection somehow shares same account?
Something was missing in the use case description. You can also search entire policy store export xml file for the account.
When XPSRegclient was called, Siteminder admin needs to complete the registration by going through admin ui, login with id/pass/ui_name, this removes temp record in policy server, and creates permanent record in policy store.
Every registered and working ui has trusted host record in store, like hostname__0 (Generated by XPSRegClient).
Same record was used for next login attempt.
Because it is trusted host, thus handshake will happen for each UI login respectively.
Hope this help.
Thanks,
Hongxu