Hi
I didn't get your requirement.
Is the two parameters created in main report or one created in main report and other created in sub report?
If the parameters are created in main report and sub report then you need to link those parameters. if you link those parameters then it will apply only one selection criteria.
if you want to link the paramters then you need to right click on the sub report and select 'Change sub report links' option--> select main report parameter and sub report parameter in the required fields.
Otherwise if the two parameters are created in Main report then you need to delete the second parameter.
Regards,
Naga.