In North Rhine-Westphalia (NRW) - Germany there exists an agreement between different regional transit operators (NRW Mobilitätsgarantie) to reimburse you a long-distance / high speed train ticket should your original regional connection be delayed by more than 20 minutes on departure. You still have to purchase a new ticket for your new connection, then afterward the costs are refunded by the operator of the original ticket.
Simultaneously Deutsche Bahn (DB) refunds 25% of the ticket price on delay of more than 60 minutes at destination.
Now imagine a trip between Dortmund and Köln on a regional train. This train is delayed by more than 20 minutes at Dortmund from a previous journey. This allows me to take me a high speed train for that route, and it just so happens that a ICE is delayed by more than 60 minutes, but now well suited for my planned departure time. So I spontaneously purchase a ticket for this train. What stops me from claiming a refund through both NRW Mobilitätsgarantie and DB, effectively earning a net 25% of the ticket price? In the eyes of the regional train operator I take a replacement service, in the eyes of DB I begin a completely unrelated journey.