I have modified your code and made below changes :-
- Might be id="accordion1" is creating some issue so I renamed this id with customTab and replaced respectively
- Added < div class="accordion-group"> for better UI
Please test it. If you need further help please update me.
Also you can copy and paste below snippet in JSfiddle and test it :-
<div class="accordion " id="customTab">
<div class="accordion-group">
<!-- Element Group Heading -->
<div class="accordion-heading">
<a class="accordion-toggle" data-toggle="collapse" data-parent="#customTab" href="#collapse1">
<b>Element Group 1</b>
</a>
</div>
<!-- Elements -->
<div id="collapse1" class="accordion-body collapse">
<!-- -->
<div class="accordion" id="accordion1-1">
<div class="accordion-heading" style="margin-left: 30px">
<label class="radio" class="accordion-toggle" data-toggle="collapse" data-parent="#accordion1-1" data-target="#collapseOne1-1">
<input type="radio" name="optionsCheckboxList" value="1"/>Element One
</label>
</div>
<div id="collapseOne1-1" class="accordion-body collapse">
<div class="accordion-inner" style="margin-left: 60px">
<!-- Sample Description -->
<input type="radio" name="selComment" value="descName" onclick="populateComment(this.value)"/>${desc1.name}<br/>
</div></div>
</div>
<!-- -->
<div class="accordion" id="accordion1-2">
<div class="accordion-heading" style="margin-left: 30px">
<label class="radio" class="accordion-toggle" data-toggle="collapse" data-parent="#accordion1-2" data-target="#collapseOne1-2">
<input type="radio" name="optionsCheckboxList" value="2"/>Element Two
</label>
</div>
<div id="collapseOne1-2" class="accordion-body collapse">
<div class="accordion-inner" style="margin-left: 60px">
<!-- Sample Description -->
<input type="radio" name="selComment" value="descName" onclick="populateComment(this.value)"/>${desc1.name}<br/>
</div></div>
</div>
<!-- -->
</div>
</div>
<div class="accordion-group">
<!-- Element Group Heading -->
<div class="accordion-heading">
<a class="accordion-toggle" data-toggle="collapse" data-parent="#customTab" href="#collapse2">
<b>Element Group 2</b>
</a>
</div>
<!-- Elements -->
<div id="collapse2" class="accordion-body collapse">
<!-- -->
<div class="accordion" id="accordion2-1">
<div class="accordion-heading" style="margin-left: 30px">
<label class="radio" class="accordion-toggle" data-toggle="collapse" data-parent="#accordion2-1" data-target="#collapseOne2-1">
<input type="radio" name="optionsCheckboxList" value="1"/>Element One
</label>
</div>
<div id="collapseOne2-1" class="accordion-body collapse">
<div class="accordion-inner" style="margin-left: 60px">
<!-- Sample Description -->
<input type="radio" name="selComment" value="descName" onclick="populateComment(this.value)"/>${desc1.name}<br/>
</div></div>
</div>
<!-- -->
<div class="accordion" id="accordion2-2">
<div class="accordion-heading" style="margin-left: 30px">
<label class="radio" class="accordion-toggle" data-toggle="collapse" data-parent="#accordion2-2" data-target="#collapseOne2-2">
<input type="radio" name="optionsCheckboxList" value="2"/>Element Two
</label>
</div>
<div id="collapseOne2-2" class="accordion-body collapse">
<div class="accordion-inner" style="margin-left: 60px">
<!-- Sample Description -->
<input type="radio" name="selComment" value="descName" onclick="populateComment(this.value)"/>${desc1.name}<br/>
</div></div>
</div>
<!-- -->
</div>
</div>
</div>