I'm trying to configure a connection to a new repository in RRC (i.e., I have an existing repository and now i'm trying to add a new one). When i use "https://myhostname:9443/rdm/" in New Repository URL link, I'm getting the following error message "A repository connection with the URL https://myhostname:9443/rdm/ already exists". What should i do to fix this issue?

Are both server repositories running on the same machine? If so the port number needs to be different, as the host name aliases if different resolve to the same machine, for example

https://Server-1.ibm.com:9443/rdm/
https://Server-2.ibm.com:9443/rdm/

Will only work if the servers are running on different physical machines. If you want them to run on the same machine then something like this is needed

https://Server-1.ibm.com:9443/rdm/
https://Server-2.ibm.com:9444/rdm/

If this the problem, and the server repository is running on the same machine, there are some instructions on this wiki page for configuring different port numbers. A little old but should still work for RRC 2.x

https://jazz.net/wiki/bin/view/Main/CALMSmokeInstall

If this is not the problem then from the RRC Client, open the Project Explorer from the left hand sidebar and ensure that there is not already a repository of that name in the explorer.

I hope this helps.