php多维数组内部合并

array(3) {
  [0] => array(9) {
    [0] => string(1) "1"
    [1] => string(3) "175"
    [2] => string(1) "2"
    [3] => string(2) "22"
    [4] => string(2) "22"
    [5] => string(2) "-1"
    [6] => string(1) "0"
    [7] => string(11) "小份+0元"
    [8] => int(44)
  }
  [1] => array(9) {
    [0] => string(1) "1"
    [1] => string(3) "175"
    [2] => string(1) "3"
    [3] => string(2) "22"
    [4] => string(2) "22"
    [5] => string(2) "-1"
    [6] => string(1) "0"
    [7] => string(11) "小份+0元"
    [8] => int(66)
  }
  [3] => array(9) {
    [0] => string(1) "1"
    [1] => string(3) "175"
    [2] => string(1) "2"
    [3] => string(2) "22"
    [4] => string(2) "22"
    [5] => string(2) "-1"
    [6] => string(1) "0"
    [7] => string(11) "小份+0元"
    [8] => int(44)
  }
}

请问如何把一样的一维数组合并
并且如果两者一样 把 [2] => string(1) "2"的值相加后的值作为新的值.键不变