This is one of the beautiful things about InfoPath. The data source and controls are somewhat separate.
You can bind as many controls as you need to a single field. If they are in the same view, you'll see a little blue "i" on the control, letting you know you have multiple controls bound to the same field, but that is just an informational message, which you can choose to ignore (as I do).
You can also use expression boxes (calculated values in IP 2010) that display the value of a field (useful for an email section, where you won't be displaying data for users to change....)
You can try this by selecting a field in your main data source, and dragging it onto your form a few times. Preview, and when you fill out the first instance, all your instances will get filled out... Fun! :-}