[рони]

repz,

let res= {};
outs =[
    {
    "sec": "12",
    "disp": "AD",
    "num": "321"
},  {
    "sec": "12",
    "disp": "AD",
    "num": "123"
},  {
    "sec": "20",
    "disp": "ND",
    "num": "123"
}];
res = outs.reduce((res, {sec, num}) => (res[`${num},sec`]=(res[`${num},sec`] || 0) + +sec, res), res);
console.log(res)