IF You Own the Rights

Medium specifically provides tools that allow you to import your own content from your own blog, so I don't think this is 100% accurate - provided you own the copyright and the right to publish the piece on Medium, and provided you do know how to use the importer or the Advanced Settings to set the canonical URL.

You should never "scrape the web" for content, nor "spin" other people's posts and articles you find there, or post stories on Medium multiple times (on your own account, or using multiple accounts).

But you can republish your own work here - once - if you retain the rights to it.

Photo by Ash from Modern Afflatus on Unsplash