I'm not aware that you can do this with Keepass which was really designed a long time ago when things were a bit simpler! However, something like LastPass will do this very easily.
Personally, I use both. LastPass for browser convenience and access from any machine but Keepass for my most secure passwords and to use the Keepass v2 features for complex, multi-page logins such as banking.
AFAIK, the best you can do in Keepass is to select the login you want and use the Keepass keyboard shortcuts to send the login to the browser. Keepass does not limit you in any way from having multiple entries all pointing at the same URL.