Which java collection allows duplicate keys
<p>Im trying to write program to remove duplicate key-value pairs of a word list. However if key is duplicated with different value, that record should be allowed to add. Please help me to understand Which java collection would be solve this situation.</p>

<ul>
<li>key1  aaaa</li>
<li>key2  bbbb</li>
<li>key3  cccc</li>
<li>key4  dddd</li>
<li>key2  bbbb - duplicate pair - not allowed </li>
<li>key1  hhhh - duplicate key - allowed </li>
<li>key5  gggg</li>
<li>key2  nnnn</li>
</ul>