[Bug Report] Multiple predefine colors are selected when only one color is clicked in ColorPicker

### Element UI version
2.15.7

### OS/Browsers version
MacOS Monterey

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/liminesredep/pen/RwjboQE?editors=1111

### Steps to reproduce
Make sure the predefine prop is provided. Then change the predefine colors so they only differ by +- 5 (for example rgba(255, 72, 0, 0.68), rgba(255, 75, 0, 0.68)). The ColorPicker is then interpreting these colors as the same color.

### What is Expected?
It is expected that the ColorPicker is interpreting these colors as different colors. When the rgba values only differ by +- 5, then the ColorPicker will interpret these colors as the same.

### What is actually happening?
When predefine prop is provided, the ColorPicker is interpreting rgba colors as the same color when the rgba values only differ by +- 5.