Duplicate content or plagiarism ?

Hi, I own and operate 3 sites. 2 Wordpress and 1 Shopify. All within same niche ( pets/veterinary ).
I am considering moving OR duplicating some of the blog articles from an older Wordpress site to the newer Shopify site.
Will search engines discount this as "duplicate content" or "plagiarism" ? I'm the author of all content on all 3 sites, and my name is all over all sites and articles.
Thank you :)