WordPress Plugin "Sticky Widgets"
By default, a widget placed in a widget area (e.g., a sidebar) appears anywhere that widget area has been displayed throughout the entire site. The Sticky Widgets plugin allows you to set specific widgets on a post or page, allowing you to override the site-wide widget areas. It does this by cloning available widget areas and storing a local version tied to the content itself. Sticky Widgets is theme-independent and uses any widget areas registered with the theme.