[Bug Report] 级联选择器回显问题

### Element UI version
2.13.0

### OS/Browsers version
windows/ Google Chrome 80.0.3987.149

### Vue version
3.0.0-alpha.10

### Reproduction Link
https://codepen.io/taogy/details/poJqoox

### Steps to reproduce
1.点击取消选择tag按钮
2.随机取消选择1-2个tag就可重现

### What is Expected?
点击取消tagA对应取消tagA

### What is actually happening?
当前选择的是tagA没有被取消，页面取消的是tagB