First Thumbnail Duplicating on Slideshow - WordPress / PHP

Hi there,

I have an issue with a slideshow on my website. It is a custom coded WordPress theme.
When I upload a new product to my store, the first photo duplicates itself in the thumbnail slider. I haven't uploaded it twice - I don't understand how this is happening.

The theme was coded a few years ago and did work, but since then when I upload new images the thumbnails appear stretched and the first is duplicating.

Here is one of the products that was uploaded a few years back and appears correctly: http://little-letters.com/?wpsc-product=picture-perfect
Here is one of the products that was uploaded yesterday and has the errors as stated above: http://little-letters.com/?wpsc-product=little-pearl

If anyone has any advice I would really appreciate it, I have a basic knowledge of PHP, but I am willing to give a donation to anyone who may be able to help me resolve this issue. I need to get my website updated asap and this has stalled me in my tracks!


Thanks for any help in advance.