Bootstrap Modal Form Submission Encoding Checkbox Name Brackets

On Bootstrap 3.3.6, I am getting a mangled query string when I submit a form (no javascript for submit) with array-named checkboxes.

The query string looks like:

?CheckboxName%5B%5D=val1&CheckboxName%5B%5D=val2

when I expect to see:

?CheckboxName[]=val1&CheckboxName[]=val2

from (stripped out irrelevant form fields):

<form class="form-horizontal" name="ModalFilter" action="">
    <label><input type="checkbox" name="CheckboxName[]" value="val1" checked>val1</label>
    <label><input type="checkbox" name="CheckboxName[]" value="val2" checked>val2</label>
    <button type="submit" class="btn btn-primary">Apply</button>
</form>

Declaring the action and method doesn't seem to help. Is this happening because the Bootstrap Modal window is an independent window with its own !DOCTYPE tag? Is my form submission getting bounced around twice before it makes it back to the original page?

I am not opposed to using javascript to submit if it is the best way forward; I thought I could manage without it.

In the end, I just need the form submission to reload the original page with the form values built into the query string.

(There are many ways I can achieve a favorable result, if this one doesn't pan out, I'll move on.) Thanks in advance.