[Bug Report] Duplicate Tag Creation Clears All Instances of the Tag in element select Component

### Element UI version
2.15.14

### OS/Browsers version
Google Chrome 125.0.6422.142 arm64

### Vue version
2.7.16

### Reproduction Link
https://codepen.io/lzbghwut-the-typescripter/pen/NWVwdNL

### Steps to reproduce
1. Use the select component with the option to create new tags enabled.
2. Add a new tag that already exists in the list.

### What is Expected?
When attempting to create a tag that already exists, the original tags should be preserved and no duplicates should be created.

### What is actually happening?
All instances of the existing tag are cleared from the list.