Many parts of the GUI, including the call-time metric display page, were redone in x.2.0 to use JSF rather than Struts. It sounds like support for multiple call-time metrics for a give Resource may have been removed during this process. Adding it back would not be too hard - just a matter of adding a pulldown menu on the page that allows the user to select which metric to display if there is more than one metric. The page is located at rhq-trunk/modules/enterprise/gui/portal-war/src/main/webapp/rhq/common/monitor/response.xhtml. Please feel free to create an issue for this at http://jira.rhq-project.org/ or even submit a patch.
Thanks for the clarification. I've filed a ticket: http://jira.rhq-project.org/browse/RHQ-2054
Is this really only a GUI issue or have you changed the way you collect these metrics as well?
It's only a GUI issue. There is otherwise no limitation on how many call-time metrics a given Resource can expose.