Describe the bug
Genetate duplicated css in dev mode
To Reproduce
I could provide a repository if you need.
Screenshots
<div p="t-10">This is a WindiCss Demo</div>
it's ok when first render.

then I change p="t-10" to p="t-15", it's still ok

but when I change p="t-15" back to p="t-10", code for p="t-10" is duplicated.
