You can also create your own field 'Revenue' as Type for the 1st type,, 'Cost' as Type for the 2nd one. So that you concatenate the tables into one single table, but can dissociate the revenues and the costs.
See page 17 of the fllowing doc.
There are a number of approaches here, but a simplest may be to JOIN the shipments to the orders. I'm not clear why you would have a 'Revenue" field on both tables. If they both represent the same data, drop the Revenue field from the Shipments table. If they are different data, rename them to have different names.
If you want to select a single date and show both Orders and Shipments for that date, you can do that by creating a link table. Here's a tutorial on how to do that: