Two sets of checkboxes sending values to two hidden fields

I have two rows of four checkboxes each with a hidden text field. I am using jquery to process the data from the ticked checkbox and place the result in the fields. However when I tick one checkbox it places the value in both fields. I have placed 2 instances of the script in the head of the page each with their own unique id. All indications are that the script is working correctly. Works perfectly if I only use one set of checkboxes. However I need two instances of the same checkboxes on my page. Any ideas would be really appreciated.