Plugin is always preloading and appending to body despite having linkstyles already in HTML

Hi,

I am using the newest version of the Plugin + Webpack4.

Since the preload feature was added, it always adds the style tags to the body despite having them already in the HTML.
In my opinion it should not add the preload tags if the stylesheets are already added to the HTML.

https://github.com/faceyspacey/extract-css-chunks-webpack-plugin/blob/master/src/index.js#L390

I think it is a bug, as I don't see any reason of adding the same stylesheet twice.

BR,
Kevin