You are probably looking for official information, maybe @Douwe can help.
But my guess is, these phones ate simply refurbished phones: Returns from customers for various reasons that have been refurbished, repaired and checked for functionality and are now resold. Several manufacturers are doing this, including Apple. I also guess it’s impossible to know who owned a specific phone before and why would you want to. It’s also not common to tell which parts precisely have been repaired or replaced.