field displayed twice on receipts

Great plugin! Having one issue:

The custom field shows properly on the product page, in the cart, and through checkout. But the field name wcpa_id_0 also shows (in addition to the public name/label) on the onscreen receipt, and the emailed receipt.

Why is this showing in those locations, and how do I suppress it.

Thanks.

The page I need help with: [log in to see the link]