Add-on Barcode Not Scanned Properly (e.g., ISBN with Additional Barcode)

[BahromjonPolat]

Describe your issue. If applicable, add screenshots to help explain your problem.

I am using the mlkit_barcode_scanner package to scan book ISBNs, and it works well for the primary barcode (e.g., EAN-13 or UPC-A). However, many books also include an add-on barcode (usually 2-digit or 5-digit), which encodes additional information such as book series or price. The scanner currently fails to detect or process these add-on barcodes.

Steps to reproduce.

1. Use the mlkit_barcode_scanner package with the default or custom barcode formats.
2. Attempt to scan a book with an ISBN barcode and an add-on barcode (e.g., EAN-13 + 2-digit add-on).
3. Observe that the main barcode is detected but the add-on barcode is ignored.

What is the expected result?

The scanner should detect both the main barcode (EAN-13) and the add-on barcode and return them together as part of the barcode result.
Only the main barcode (EAN-13) is returned. The add-on barcode is not detected or included in the result.

Did you try our example app?

Yes

Is it reproducible in the example app?

Yes

Reproducible in which OS?

Android

Flutter/Dart Version?

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.27.0, on Ubuntu 22.04.5 LTS 6.8.0-49-generic, locale en_US.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[✓] Android Studio (version 2024.1)
[✓] VS Code (version 1.95.1)
[✓] Connected device (3 available)
[✓] Network resources

Plugin Version?

google_mlkit_barcode_scanning: ^0.13.0