Posts have a canonical reference to the originating instance, e.g. this post contains <link data-inferno-helmet=“true” rel=“canonical” href=“https://aussie.zone/post/11962005”> for me. This is a hint for search engines to ignore this post and instead index the original one instead. The same also already works for communities, this community containing <link data-inferno-helmet=“true” rel=“canonical” href=“https://aussie.zone/c/meta”>. Not sure if DDG is just ignoring this or there’s another reason for it to show up multiple times.