How to have multiple instances of the same taxonomy in a search form

jpd527,

Please remember that ‘tag’ is singular and not plural. Here your form has multiple HTML element with same id so this is wrong. Now if you require to search data with two different inputs, then you can merge it via JS.

HTML code like:

<form method="get" id="search form" action="https://wordpress.stackexchange.com/">
<div>
<input type="text" value="" name="tag_one" id="tag_one" />
<input type="text" value="" name="tag_two" id="tag_two" />
<input type="hidden" name="tag" id="tag" value=""/><!--Tag is hidden, combine of tag_one and tag_two-->
<input type="hidden" value="94" name="cat" id="scat" />
<input type="submit" id="search_submit" name="Search" value="Search"/>
</div>
</form>

JS code like:

document.getElementbyId('tag').value = document.getElementbyId('tag_one').value +" "+ document.getElementbyId('tag_two').value;

This is build url like http://yoursite.com/….&tag=abc+xyz. And it will automatically give result arround your tags input.

OR

You can use wordpress provided plugin: https://wordpress.org/plugins/multiple-tags.

Thanks!