What is the dual category control
Transactions that are entered into your accounts contain various parts of information - the amount, the payee, check numbers. In addition, there is a field called the category. This field allows you to provide information to divide up your spending in a manner that allows you to identify, across accounts, where spending (or earning) is taking place.
Use of this field allows you, for example, to see how much you pay in taxes, or how much your car costs.
In addition to this wider view, there is also a subcategory - this allows for further granularity, and so you could look to see how much you spend not just on Taxes, but on State Taxes. Similarly, in addition to having details about all of your vehicle spending, the category can be subdivided to show you your gasoline expenditure.
Putting in category and subcategory information also helps with creation of the budget and reports that track income and spending.
When entering category information using default settings, Money provides a single dropdown list which contains all of the information. For example, all categories and subcategories are listed in one list, which could conceivably be quite long.
Some people prefer the list to be split into two parts - one with the category, and another with the subcategory. The latter would show only those subcategories which belong to the category selected (or all, if no category is selected). This is the dual category control, and is shown below.
You must be using the Advanced account register to see the dual category control. The behavior can be changed by going to Tools->Options, select 'Category' and check or uncheck the 'Dual Category Control' option.