We have a Zebra 105SL Plus for the labels of our products. And we have a major issue concerning our UPC printing, sometimes the printed label would have a modified barcode than the one that was designed in Label Matrix, although the UPC number is right the barcode isn't and although it doesn't happen often, its a huge pain to realize our warehouse returned the product cause of wrong codes and it just delays the whole process of getting it to our costumers. I've been looking around for solutions online with no success, re-calibrated the printer, re-installed the software. And the issue persists, any leads as to the possible reasoning behind this would be greatly appreciated. 

We design one single label in our software which then proceeds to print in a 3-column label roll. When this error happens it usually happens along a whole column, could be any of the three columns this roll has.

I attach an image with 2 codes from the same batch for reference. 

[![enter image description here](https://i.stack.imgur.com/Y4vnX.jpg)](https://i.stack.imgur.com/Y4vnX.jpg)
[![enter image description here](https://i.stack.imgur.com/VIBhl.jpg)](https://i.stack.imgur.com/VIBhl.jpg)

You can see how although the same UPC number the barcode is different.

The event hasn't repeated (Thankfully) but I would hate to face this issue again in the future without knowing what's causing it. I have added better quality images.