I need to compare the same "PhoneNumber" attributes having the same "ID" for each element
<List>
<Connect ID="ID1" PhoneNumber="453585644878">
</Connect>
<Connect ID="ID1" PhoneNumber="453585644878">
</Connect>
<Connect ID="ID2" PhoneNumber="45655556658">
</Connect>
<Connect ID="ID2" PhoneNumber="96685688787">
</Connect>
<Connect ID="ID3" PhoneNumber="5766855577">
</Connect>
<Connect ID="ID3" PhoneNumber="8565657787">
</Connect>
<Connect ID="ID3" PhoneNumber="4565775235">
</Connect>
<Connect ID="ID4" PhoneNumber="44545454545">
</Connect>
</List>
for example in , the first two connect equivalent phone numbers and in the other non-equivalent numbers.