How to Copy a Page in WordPress

Thanks for useful video. I have bought a theme having one page called service. If I don't make any changes to the original page, this plugin works fine. But if I make some changes to the page, then clone the changed page, it seems the plugin only copy the content while other things (images, styles, links,...) is lost. I don't know why. Could you please give an advice? I followed exactly your guidance about this plugin (Yoast Duplicate Post). Thank you.