Preventing Duplicate Barcode Scans in Elo/Zebra Scanners Using 123Scan

Some customers report that when an item remains in front of the scanner, the same barcode is decoded multiple times. This can result in:

• Duplicate items added to the transaction

• Customers being charged more than once

• Incorrect cancellation reporting

• Skewed inventory counts

This behavior is expected when a scanner is operating in Presentation or Continuous Read mode without a same-symbol lockout.

Root Cause

By default, the scanner will continue to decode the same barcode as long as it remains in the field of view. Without a delay or filter, the same UPC can be sent repeatedly to the host application.

Resolution

Configure a Same Symbol Timeout using Zebra’s 123Scan utility.

Configuration Steps (Zebra 123Scan)

1. Launch Zebra 123Scan and connect the scanner.

2. Load the scanner configuration.

3. Navigate to:
   General → Timeout Between Same Symbols 

   • (Default is 600ms)

4. Set the value to a non-zero delay. Recommended starting point:

   • 1000–3000 ms (10–30 in the field, since values are in x100 ms units)

5. Apply the configuration to the scanner.

What This Setting Does

The Timeout Between Same Symbols parameter prevents the scanner from decoding the same barcode again until:

• The item is removed from the scan field, and

• The timeout period has expired

This forces a “remove and re-present” behavior and eliminates unintended duplicate scans when an item is held in front of the scanner window.

Notes

• This setting is most important when using Presentation Mode or Continuous Read Mode.

• The exact field name may appear as:

  • Timeout Between Same Symbols

  • Same Symbol Timeout

• Attribute ID in Zebra scanners: 137

Recommended Use Case

Self-checkout, kiosks, vending, and any unattended scanning environment where an item may dwell in front of the scanner.