Sounds like the POS software isn't controlling the reader well, maybe because it wasn't adjusted for this model of reader. Or the reader's firmware could have

Sounds like the POS software isn't controlling the reader well, maybe because it wasn't adjusted for this model of reader. Or the reader's firmware could have been misconfigured, from what it's supposed to be for that POS setup. The modern reader firmware tend to have multiple modes and many options. Some modes are as simple as "scan whatever you see out of the many formats you support, and spit out the decoded value of something as USB Serial". Or, worse, "...as USB Keyboard". You can imagine how easy those modes are to integrate with POS software, without implementing the proprietary protocol for that device, and you can also imagine how poorly that can work out. If you owned a store with a POS setup with flaky reader behavior like this, and were stuck with it, you could try reconfiguring the reader (to, say, disable QR support). This reprogramming can sometimes be done via documented protocol, via sketchy Windows software, or via... barcode... Careful you don't make it worse. (Our startup used modern readers (multiple 1D formats, QR, NFC) for a factory station, and had to do a lot of experimenting with different brands and models, to get the behavior and speed we needed. We even managed to brick a reader, just with configuration changes, not flashing firmware.)