Are you using a subreport? I see this when linking the parameter to a subreport. If so, you need to link via parameter in the subreport and not select the default parameter that CR wants to create for you.

I don't get it. When do you get prompted? Is it for each new page? Maybe there is a formula that uses the fields and is causing it to be prompted a second time?

I see. You're using the same parameters for two different purposes and it is prompting you for the parameters each time. I'm not sure how to fix this. One idea is to make this a subreport of a blank main report. The blank main report will get the prompts and then pass them to the subreport which can use them in the query and command objects.