Yes, but you've booked them as two point to point tickets. BA's responsibility and liability on the first ticket is to get you from A to B. As long as they do that, job done - there's nothing that says they have to get you there in time for your B to C flight. The fact that you're going from B to C with BA later that day isn't a concern with regard to BA's liability/responsibility to get you from A to B.

If you'd booked to travel from A to C, via B, different story. In this scenario, BA is contracted to get you to C, and bears the cost of changing your flights etc in the event that A to B runs late. That's why the A to C ticket costs more normally.

Is there any flexibility in your LHR - MUC ticket? And how long did you allow between the flights?