WordPress Child Theme

I created a theme called WP-Forge and then I created a child theme to be used with WP-Forge called WP-Starter https://wpstarter.themeawesome.com/

When I created WP-Starter, the method of @import was still being used and now I see that there is a new way of pulling in the parent css: https://codex.www.ads-software.com/Child_Themes

However, when I updated WP-Starter to use this new way of pulling in the parent css, it seems that I get two versions of WP-Starter’s style sheet. If you look at the source of https://wpstarter.themeawesome.com/ – you will see that wpforge-css is exactly the same as child-style-css

Just wondering if anyone can help by explaining why this may be happening so I can correct it?

Your help is greatly appreciated and thank you in advance.