lost and found

Feb 27, 2018
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Ok so I lost my iPhone at the gym, couldn't find it anywhere. I reported a claim it was lost then I got a brand new iPhone to replace the lost one. Then a few days later the lost iPhone was found and returned to me. Now I have the new iPhone that I use and the old iPhone that i don't use. My question is can I sell my lost phone that was returned, it isn't stolen or someone else's lost phone. It was my phone I lost and i was wondering if it is illegal to sell the old iPhone?