ssrs 2008 error message, variable name '@pC' has already been declared. variable names must be unique within a query batch or stored procedure. "

In an existing SSRS 2008 report, I am getting the following error message when I run the ssrs report:
"query execution failed for dataset 'getMilestones'. The variable name '@pC' has already been declared. variable names must be unique within a query batch or stored procedure. "
The parameter called 'pCustomerNumber' is the only paramter by that name that I can see. This is a cascading paramter. There are at least 2 parameters that reference 'pCustomerNumber'. Thus I am not certain what could be wrong. Could the order of how the parameters str declared make a difference?

Would you let me know what you think is wrong so that I could try to resolve this iss