[Arramis]

webphp,

function getUnique(data) {
    var i = 0, j = 0, l = data.length, res = [];
    
    for ( ; i < l; ++i ) {
        for ( j = i; j < l; ++j ) {          
            if (i != j && data[i].group == data[j].group && data[i].version == data[j].version) {
                res.push(data[i]);
                continue;
            }
        }
    }
    
    return res;
}

var inputArr = [
  { group: 'group-sedan', version: 'iv' },
  { group: 'group-sedan', version: 'iv' },
  { group: 'group-wagon_5', version: 'iv' },
  { group: 'group-wagon_5', version: 'iv' },
  { group: 'group-sedan', version: 'iii' },
  { group: 'group-sedan', version: 'iii' },
  { group: 'group-wagon_5', version: 'iii' },
  { group: 'group-wagon_5', version: 'iii' },
  { group: 'group-wagon_5', version: 'ii' },
  { group: 'group-wagon_5', version: 'ii' },
  { group: 'group-sedan', version: 'ii' },
  { group: 'group-sedan', version: 'ii' },
  { group: 'group-coupe', version: 'i' },
  { group: 'group-coupe', version: 'i' },
  { group: 'group-sedan', version: 'i' },
  { group: 'group-sedan', version: 'i' }
];

console.log(getUnique(inputArr));

позже сделаю с двумерным массивом