var arr = [ 

     { 

       SortTime: 123456, 

       Operation: 'first operator'

     }, {

       SortTime: 4567,

       Operation: Assigning

     }, {

       SortTime: 123456,

       Operation: 'second operator'

     }];

​

console.log(arr)

var copy = [...arr];

​

copy.sort(function(a, b) {

    if (a.val.SortTime === b.val.SortTime) {

        return arr.indexOf(a) - arr.indexOf(b);

    } else {

        return a.val.SortTime - b.val.SortTime;

    }

});

​

console.log(arr)

console.log(copy)