In the web app, there is a view that summarizes tasks on the chosen list. You can see the number of tasks, how many of them are due today, and so on...

When you select one task, of course, you will see the details of it. However, if you select two or more, on the big blank background, you will see only a number of selected tasks with the option to deselect them.

The idea is to use the same view that summarizes tasks on the list before any of them is selected to show the same statistics, but about only the selected (two or more) items. It could be very helpful to see the sum of estimated time for selected tasks (not only the sum for all of them).