Actually Discord if you look into almost any PS1 booklet just inside one the first page to the left it will say somewhere "Backup copies prohibited" or "Making copies of this disk is illegal" or something to that effect. I've seen that message thousands of times on thousands of games.

Sorry man it's definately illegal, its just your not likely to get busted by the police for it, just like when you record a fav TV show of yours with a VCR...technically that is copying copywrited material without the onwers consent but no-one cares.