In addition, I build an app with the same "Barcode scanner for PhoneGap" widget as Wieke. What we experienced is not that it scans the wrong text but while processing and emptying the input and then scanning a new barcode it cuts off part of the new barcode when it still was processing the last scanned barcode. What I did in the end was creating a barcodeScanned object and then pass it to an execute microflow in background java action to process it further. Therefor minimizing the process time of a scanned barcode and it fixed this behaviour at our side. For processing it in background I used a persistent item. The reason was that I displayed a list of the scanned barcodes and wanted to show the results there of the processing, when using a non-persistent item this i not possible when executing in background.
Are you using the "Barcode Scanner for PhoneGap" widget? And how do you test, using Mendix (developer) app or by generating a file that you can install on your phone? And is this behavior on both ios and android?
I recently created a similar app, and experienced different kind of behavior in all of the above described scenarios. Testing using the (discontinued) Mendix Developer App gave the best results in the end