modified code originally posted by Ghanshyam Katriya(anshkatriya at gmail) [highest voted comment here].

1. In php 7.4 counter $i breaks the function. Removed completely (imo was waste of keystrokes anyway).
2. I added second return value - array of duplicates. So you can take both and compare them (I had to).

Example array (copy-paste from original post):
<?php
$details = array(
    0 => array("id"=>"1", "name"=>"Mike",    "num"=>"9876543210"),
    1 => array("id"=>"2", "name"=>"Carissa", "num"=>"08548596258"),
    2 => array("id"=>"1", "name"=>"Mathew",  "num"=>"784581254"),
);
?> 

Function:
<?php
function unique_multidim_array($array, $key) : array {
    $uniq_array = array();
    $dup_array = array();
    $key_array = array();

    foreach($array as $val) {
        if (!in_array($val[$key], $key_array)) {
            $key_array[] = $val[$key];
            $uniq_array[] = $val;
/*
            # 1st list to check:
            # echo "ID or sth: " . $val['building_id'] . "; Something else: " . $val['nodes_name'] . (...) "\n";
*/
        } else {
            $dup_array[] = $val;
/*
            # 2nd list to check:
            # echo "ID or sth: " . $val['building_id'] . "; Something else: " . $val['nodes_name'] . (...) "\n";
*/
        }
    }
    return array($uniq_array, $dup_array, /* $key_array */);
}
?> 

Usage:
<?php
list($unique_addresses, $duplicates, /* $unique_keys */) = unique_multidim_array($details,'id');
?>

Then:
var_dump($unique_addresses);
or
var_dump($duplicates);
or foreach or whatever. Personally I just echo-ed 1st and then 2nd (both DOUBLE COMMENTED) list in function itself (then copied both to notepad++ and compared them - just to be 100% sure), but in case you want to do something else with it - enjoy :)
Plus - as a bonus - you also get an array of UNIQUE keys you searched for (just uncomment >$key_array< in both: function return and function call code).

From example array code returns:
var_dump($unique_addresses); 
array(2) {
  [0]=>
  array(3) {
    ["id"]=>
    string(1) "1"
    ["name"]=>
    string(4) "Mike"
    ["num"]=>
    string(10) "9876543210"
  }
  [1]=>
  array(3) {
    ["id"]=>
    string(1) "2"
    ["name"]=>
    string(7) "Carissa"
    ["num"]=>
    string(11) "08548596258"
  }
}

var_dump($duplicates); 
array(1) {
  [0]=>
  array(3) {
    ["id"]=>
    string(1) "1"
    ["name"]=>
    string(6) "Mathew"
    ["num"]=>
    string(9) "784581254"
  }
}

Plus keys, if you want.

P.S.: in my - practical - case of DB querying I got around 4k uniques and 15k dupes :)