So what I think you're saying is that these "duplicate" records may appear anywhere on the report - they won't be grouped together, correct? If this is the case, then I don't think there is a way to do this. If they are grouped together, then you can use David's information about formatting the font, but use a formula like this to set the color:
If ({table.description} = previous({table.description}) ) and
{table.cost} = previous({table.cost}) then Red else Black
-Dell