This is going to sound a little bit dumb but when a UPC starts with a zero it is unnecessary. in fact barcode scanners often leave them off when products are scanned. its only necessary information if it starts with an 8 or some other number other than zero. additionally when it starts with a zero it also ignores the last number. that's how we have 10 and 12 digit UPC numbers even though all UPC's are actually 12 digits long.
so for your example a barcode scanner really only reads "0911992051" where as the barcode may actually be "009119920513" printed on the box