let score = [10,2,3,3,2];
let doublon = [];
for (let i = 0; i < score.length; i++) {
    var temp = score[i];
    for (let j = i+1; j < score.length; j++) {
        if (temp === score[j]) {
            doublon.push(temp)
        }
    }
}

console.log(doublon);