What is the business purpose of scheduling two separate flights on the very same route with 5-10 minutes separation?
If you look at just the schedules it says nothing. If you look at the prices you can see that Air Berlin was pricing the flight significantly lower than Air France. As was stated above, it was competition.

Unfortunately, things did not end well for Air Berlin. The airline declared bankruptcy in August 2017, and was unable to obtain further funds from its primary shareholder, Etihad. The company closed its doors in October of the same year.