Creating a new tag with a value equal to the id of an existing option causes both the new tag and the existing option to be added as selections

Description

// input: red,
// var_dump($_POST["colors"]);
Array
(
    [0] => red
    [1] => red
)

// input: apple,green,water,
// var_dump($_POST["colors"]);
Array
(
    [0] => green
    [1] => green
)

// input: red,green,blue,yellow,
// var_dump($_POST["colors"]);
Array
(
    [0] => red
    [1] => green
    [2] => blue
    [3] => yellow
    [4] => red
)

<select name="colors[]" id="tags-example" multiple="multiple">
    <option value="red">apple</option>
    <option value="green">grass</option>
    <option value="blue">water</option>
    <option value="yellow">sun</option>
</select>

$('#tags-example').select2({
    tags: true,
    tokenSeparators: [',', ' '],
    maximumSelectionLength: 2
});

Contributor guide

Tech stack

javascript

Domain

frontend

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

2

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

None

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

80

Research direction

Investigate the Select2 source code, specifically the tag creation logic in `src/js/select2/data/tags.js`. The bug occurs when a new tag's value matches an existing option's value; the code adds both the tag and the option. Focus on the `createTag` function and how it interacts with the data store. Review the issue comments (#3498) for any additional context or proposed solutions.