A real-world example for a kind of real-time applications
Example 1: Playing a multimedia stream where Task 1 must decompress an audio "frame" while Task 2 must decompress a video frame by the same deadline: the playback time for a given video frame.

This is a little unrealistic though because in practice there's a demux task that task 1 and 2 both depend on, and usually the audio and video playback frames have different repeating deadline frequencies.

Example 2: A robot might run all its control loops with the same frequency for simplicity. The control loops all depend on receiving a new set of sensor input values, then they all run, and they all send outputs to the actuators. E.g. Task 1 controls the motor for the left side of the tank drive, Task 2 controls the motor for the right side of the tank drive, while Task 3 controls the robot arm. It just simplifies things a bit to give all the control loops the same deadline unless there are interdependencies such as needing to mux the actuator control data into a single packet to send over a network to the actuators. In that case, a Mux task depends on all the control loop tasks.