Textures cannot be verifiably owned
So if you duel art and lose you're still the owner of it ?
Depends. If you send the person the texture after losing, stating that the art is theirs, you have forfeited all rights to it. If you don't send it, no actions will be taken against you, since art duels are not supported.
So if i buy a head texture from someone who lost a duel but didin't sent ... as you said here, am still the right owner of it right ?