Input ID issues when using fieldset_text within group

When adding fieldset_text within a group the ID of the input element does not render correctly and there ends up being multiple elements with the same ID.

I have a group with an id of "ditty_slider_display". The fieldset_text field has an id of "fieldset_text" and the options are: "paddingTop, "paddingBottom", "paddingLeft", "paddingRight".

When the inputs render they are as follows:

<input size="30" type="text" id="_ditty_slider_display_" class="rwmb-fieldset_text" name="_ditty_slider_display[padding][paddingTop]">

<input size="30" type="text" id="_ditty_slider_display_" class="rwmb-fieldset_text" name="_ditty_slider_display[padding][paddingBottom]">

<input size="30" type="text" id="_ditty_slider_display_" class="rwmb-fieldset_text" name="_ditty_slider_display[padding][paddingLeft]">

<input size="30" type="text" id="_ditty_slider_display_" class="rwmb-fieldset_text" name="_ditty_slider_display[padding][paddingRight]">