foundation-sites: Abide validation statuses triggered twice.

Provided a simple form as the one from Foundation 5 Docs:

<form data-abide="ajax" id="myform">
    <div class="name-field">
        <label>Your name <small>required</small>
            <input type="text" name="users_name" required pattern="[a-zA-Z]+">
        </label>
        <small class="error">Name is required and must be a string.</small>
    </div>
    <button type="submit">Submit</button>
</form>

and a simple jQuery piece of code to handle abide validation

$('#myform').on('valid.fndtn.abide', function(e) {

    // Handle the submission of the form
    console.log(e);
});

THAT console.log is always fired twice!

Did any of you encountered the same issue? Any help please? Thank You.