Upvote:3
If he didn't inform the police, I can understand his passport wasn't marked as lost.
In many countries, one can have 2 valid passports simultaneously, so it's not surprising your friend was easily able to obtain a second passport.
He most likely has broken a law by not filing a police report. Moreover, he may legally be responsible for many actions taken by a person(s), who found/stolen his passport.
What he should do is talk to a lawyer and I am very serious here, because not being able to renew a passport may be his least worry.