You have to change the name and id of your radios. And the labels. Like this
<div class="stars">
<div class="rating" style="width:65%"></div>
<input type="radio" name="rating" id="star5" value="5">
<label for="star5"></label>
<input type="radio" name="rating" id="star4" value="4">
<label for="star4"></label>
<input type="radio" name="rating" id="star3" value="3">
<label for="star3"></label>
<input type="radio" name="rating" id="star2" value="2">
<label for="star2"></label>
<input type="radio" name="rating" id="star1" value="1">
<label for="star1"></label>
</div>
<div class="stars">
<div class="rating" style="width:65%"></div>
<input type="radio" name="rating_2" id="star5_2" value="5">
<label for="star5_2"></label>
<input type="radio" name="rating_2" id="star4_2" value="4">
<label for="star4_2"></label>
<input type="radio" name="rating_2" id="star3_2" value="3">
<label for="star3_2"></label>
<input type="radio" name="rating_2" id="star2_2" value="2">
<label for="star2_2"></label>
<input type="radio" name="rating_2" id="star1_2" value="1">
<label for="star1_2"></label>
</div>