It's time I logged this hear so I can remember what the problem is when I get it. :)
When using a Stored Procedure in a Dataset in Reporting Services, Have you ever seen double the parameters on the refresh dialog in the Data Tab? They are actually listed twice in the dialog like this.
OrderId
OrderItemId
ProductID
OrderId
OrderItemId
ProductID
This is caused by duplicate versions of the Stored Procedure. For example
dlloyd.apGetOrder
dbo.apGetOrder
If you remove one of the Stored Procedures the parameters will return to normal.