Accidentally received full refund and travel insurance payout

I've been a bit of an idiot and stumbled into a situation I'm not quite comfortable with where I think I have unintentionally committed insurance fraud.

This in involves an airline and a travel insurance company, and a transaction where I have ended up getting a full refund and an insurance payout for the same transaction after a holiday I wasn't able to go on.

The timeline is as follows:

• I cancel the flight tickets. Airline give only a small refund (20% of transaction amount). • I submit a travel insurance claim for the remaining 80% of the funds. I then do not hear anything from the insurance company about the claim being accepted or denied for weeks. • In the meantime, I find out that the Airline has a special process for claiming additional refunds under specific emergency circumstances. This could apply to my situation, and could mean getting a refund for the remaining 80% of the funds that earlier were considered non refundable. I submit this further refund request. • I receive the refund from the Airline of the remaining 80% of the transaction cost. Yay, I now have a full refund from the Airline!! • Literally later the same day I receive a confirmation from the travel insurance company (weeks since I submitted the claim), saying that my claim was accepted and they'll pay out my claim...

So I now have double the cash... I shouldn't keep it, right? I feel like I should return it, but to whom? Presumably to the insurance company? Would I be in trouble if I admitted this whole situation to them?

Or should I contact the airline and try to return their refund instead?

Thanks!

I am based in England, as is my travel insurance. The airline is non-UK-based.