Edit: Added working JSFiddle
I am using Twitter Bootstrap TagsInput with Bootstrap Typeahead. My source is a json file, but that doesn't matter, and I checked it with a static source.

Typeahead and taginput operations work, however, when I press enter, tab or click on a tag, it creates a duplicate.

This extre 'default' happens whenever I press enter or end typeahead. If I break typeahead by separating the comma or diverting attention from the window, this will not happen.
Here is the input:
<input id="itemCategory" type="text" autocomplete="off" class="tagsInput form-control" name="itemCategory">
And here is the script:
<script> $('.tagsInput').tagsinput({ confirmKeys: [13, 44], maxTags: 1, typeahead: { source: function(query) { return $.get('listcategories.php'); } } }); </script>
I am sure that this is something shaky that will not be reproduced, with my luck, so I hope that someone will have some kind of institutional knowledge that, as they know, will cause something like that.
Here is an image of additional text in dev. tools: 
I really appreciate any advice or suggestions. Thanks.
WORK CODE
Thanks to @Girish, the following problem has been βfixedβ. I believe this is a bug at this point in time, introduced somewhere in the newer version of jQuery or Typeahead. This code simply removes the excess element manually, although I hope that something will come to prevent it from being placed there, first of all, excluding additional code. So far this works for me.
$('.tagsInput').tagsinput({ confirmKeys: [13, 44], maxTags: 1, typeahead: { source: function(query) { return $.get('tags.php'); } } }); $('.tagsInput').on('itemAdded', function(event) { setTimeout(function(){ $(">input[type=text]",".bootstrap-tagsinput").val(""); }, 1); });