For one thing, when you receive multiple notifications from the same app, there is no indication as to exactly how many notifications you've received. (android.gadgethacks.com)
Whenever you receive multiple notifications from an app, the notification icon in your status bar will have the count displayed with a small badge. (android.gadgethacks.com)
It'll become easier to keep track of multiple notifications from the same app, thanks to the new notification channels and notification dots features. (androidcentral.com)