Two Registrar under single sip-ua

[Yasir@1995]

When I have configured SIP-UA, I can see two registration requests are sent to ITSP. But only one SIP_UA is configured.  attached image for reference. 

[b.winter]

You cannot use 2 SIP registrations under SIP-ua

You need to use tenant configuration instead, that's they way you configure SIP trunks "today" on CUBE. SIP-UA isn't used anymore, only for common settings.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-cube-multi-tenants.html

[Yasir@1995]

We only have one registrar. But in the attached you can see .* registrar is auto-generated. I am here to investigate why it is auto-populated as we have several other routers with the same SIP-UA configurations. 

[b.winter]

It was just an advice. SIP-UA is not "state-of-art" anymore. Even if you only have 1 SIP-registration, the "standard" is to use tenants.
I have never seen your ".*" registration, but maybe you can post the full config. Just seeing the small output doesn't provide the full context.

[Yasir@1995]

The running config is attached.