They are not always in the same location either and without a file extension.
There's a little more info on this page
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Basically you change the conditions to unlock a trophy, like if a game had a trophy for reaching maximum rank in multiplayer and a trophy to complete the tutorial you copy the conditions from the tutorial trophy and paste it over the conditions of the maximum multiplayer rank trophy then play the tutorial to unlock max rank trophy.
Only some games use this system and only works with full game backups like in multiman, you can choose individual trophys to pop or all of them.