Several users are reporting that the latest incident (Hurricane Irma, Event ID 61) appears twice in the drop-down menu. While we cannot reproduce the error locally, users have submitted screenshots showing the error (confirmed in at least Chrome), as well as the following HTML:
<label>
<select id="incident-chooser">
<option value="61" selected >Hurricane Irma</option>
<option value="61" selected >Hurricane Irma</option>
<option value="60" >Hurricane Harvey</option>
<option value="59" >West Virginia Flood, Jul 2017</option>
<option value="58" >Illinois-Wisconsin Floods Jul 2017</option>
...so it is a confirmed error. It's apparently harmless, but confusing.