the hash mark means you are using IDs to select elements. there should however never be more than one element in your page with the same ID. for instance,
<input id="test" /><input id="test" />
is invalid HTML.
The second problem, is that it appears you are trying to find tag names, which means you should simply leave out the hash mark from your code, and JQuery will apply your methods to all of the tags with that tag name,
$("input").autocomplete("samefile.php");
will apply autocomplete to all input tags on your page.
Third, I would use classes instead of tag names incase you ever want to have an input on your page that does not use the same auto complete. So your html would look like this,
<input class="auto" /><input class="auto" />
and your JQuery would look like this.
$(".auto").autocomplete("samefile.php);
I also wonder where you are calling your JQuery from?