Checkbox value double output on if else if

whats wrong with this code :

function calculateAddOnPrice() {
        if (totalPrice <= 47) {
            var polybags= $('#polybags').is(':checked') ? "0.5" : "0";            
            console.log(polybags);
        }
        else if (totalPrice >= 48 && totalPrice < 71) {
            var polybags = $('#polybags').is(':checked') ? "0.35" : "0";            
            console.log(polybags);
        }

So i have the output logged to console.

When totalPrice is less than 47 and i click the checkbox for ON the console looks like this :

0.5

When i untick it for OFF i get this :

0

It totalPrice is > 48 and i tick the box, i get the output :

0.5
0.35

And if i untick it, i get :

0
0

I have no idea why its giving me double values, can someone help me? :)

UPDATE-----

Full jQuery : https://pastebin.com/DYV92cj3

HTML for this section :

<div class="checkbox">
    <label><input type="checkbox" id="polybags">I WOULD LIKE POLY BAGGING</label>
</div>