Years ago I flew to GIG from MIA and left my passport at the counter where you had to arrange for a taxi at GIG (before the days of Uber/Lyft). I realized it when I tried to check in at the hotel. The hotel got me to the US Consulate where I was able to get a replacement (costing me $200). This was is when Brazil required US Citizens to have a Visa adhered to one of the passport pages.
Eventually when I left I went to the Lost and Found at GIG and they had my old passport. When I got to exit customs I had to try to explain in very broken Portuguese of why I had 2 seemingly active passports and the visa in one of them. The woman just shook her head and waved me through not really wanting to hear my situation.