If you're being prompted to redeem a key multiple times, it's likely that you may need to redeem your other outstanding Steam keys too.
The Elite Dangerous Commander Deluxe Edition contains a total of three Steam product codes that you must register to your account here.
You can review your Steam product codes for Elite Dangerous by right clicking the game's entry in your Steam Library and selecting "View CD-key" from the context menu.
Should you require further assistance getting your keys attached to your account please ensure you include them in your support ticket.
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