I've heard that Google deranks content it believes to have been duplicated, and I don't know if that's really true but I've been paranoid about copying my existing Medium content to my new blog; if it's true then Google will certainly give precedence to Medium.

It is true yes, that's why the generated blog have a canonical link to medium so that the SEO isn't impacted. So you won't get any SEO for the articles that have been created on Medium but if you create one on your blog first and then import it on Medium (using the import tool, not copy pasting the content), Medium will be nice and put a canonical link pointing to your blog.

Unfortunately, it's not possible to set a canonical link on Medium a posteriori.

I don't believe your blog would get any improved SEO benefit from having canonical links to Medium - IIRC, Medium would get the juice.

Furthermore, I don't know how Google handles cross-domain canonical reporting, but if I were writing a search engine, I would treat it as highly suspect.

You've got it backwards. There will be a header in the Medium post saying "the original source for this content is on this other blog, I'm just a repost". Google does pay attention to that and ranks the canonical source higher.

I believe they were discussing how Medium does not allow canonical links. I am aware of how canonical links work.

> Unfortunately, it's not possible to set a canonical link on Medium a posteriori.

Yeah, that's a problem. :/ I guess I'll continue rewriting my old content so I at least have a shot.

Google is smart enough to handle duplicate content. It's a false problem.

From the source: https://www.youtube.com/watch?v=mQZY7EmjbMA

It’s Ok to republish content as long as you provide a link back to the original. That tells Google which version to prioritize.

Link to the post on your new blog from the Medium post.

Something like the following:

> Source: https://example.com

This should transfer link equity to your new blog post that helps offset any duplication penalty.

https://yoast.com/duplicate-content/#linking-original

Medium used to allow custom domains. They no longer do.

I left Medium, but because I own all of the URLs no links broke. Nor are there duplicate copies with canonical links. So there’s no SEO risk.