There are several ways to do this, it would be more interesting if you make the current code available.
Anyway look at the code below. Maybe I can give you a light on what to do. If that does not help, let me know that I can think of something to help you.
<?php
print_r($_POST);
?>
<div>
<form method="post">
<div>
<label> Campo 1 </label>
<input type="text" name='campo[]'>
</div>
<div>
<label> Campo 2 </label>
<input type="text" name='campo[]'>
</div>
<div>
<label> Campo 3 </label>
<input type="text" name='campo[]'>
</div>
<button> Enviar </button>
</form>
</div>
The result for the furmulario above is:
Array
(
[campo] => Array
(
[0] => 11
[1] => 22
[2] => 33
)
)
Note that by adding the '[]' at the end attribute 'name' of the input PHP will understand that it is an array. When duplicating the fields of the address you will have for example a field CEP being an array in PHP:
Array
(
[cep] => Array
(
[0] => 74063-470
[1] => 75266-392
)
)