Lufthansa will book any number of tickets for the same flight for the same day for the same first/last name person with the same frequent flyer number on the same Lufthansa portal account - and it will gladly keep the money refusing the refund.
On more than one occasion I had their website crash on me and booked ticket never showed up as booked. Never showed up on the profile and the credit card charge showed up weeks later. Of course usually after I bought a real ticket.
No amount of documentation (I always do Snipe when I do LH and non-US bookings) resulted in the refund by LH. But the credit card dispute worked - but only after I demanded their documentation. They did send some internal printouts none of which could be tied to me, and they sent the proof of ticket purchase for an itinerary between different city-pair for a flight 2 years earlier for some strange looking name. I had to force-point it to the credit card before they approved my dispute.