let songs = {};
let total= 0;
document.querySelectorAll("ytmusic-playlist-shelf-renderer .title-column").forEach(it => {
let k = it.textContent.replace(/[\n\r]/g, '').replace(/[\s]{2,}/g, '');
if(songs[k] == undefined){
songs[k] = 0;
} else {
total++;
songs[k]++;
console.info(`Duplicated song: ${k}, times=${songs[k]}`);
}
});
console.info("total duplicated songs: ", total);
Now you can find the names on the browser using CTRL + F
and remove them.