Order Summary/Details Duplicate Key Error

Using eCart 4.5.2 (originally developed with eCart 2-3 years ago using previous versions). We have a single product with two color options and have the Add to Cart functionality adding unique items for each color selected. If the user only purchases one color, everything works fine, however, if the user purchases two colors, I get a duplicate key error because the page is attempting to save summary details to the db a second time (once for each unique item in the cart?).

I've made sure that the Add Summary to DB and Add Details to DB server behaviors are set to "before page load". I receive the error before the page loads and have confirmed that the summary (1 record) and details (2 records) have been saved to the db successfully.

I'm at a loss with what to do next. Any guidance would be greatly appreciated.

Thanks,
Dawn