Members help other members with technical questions and problems using Writing.Com!
While we can't speak for those publications of which you speak... Writing.Com does not consider itself a "publishing" venue. We're an online writers community where members share work for critique and review. That said, each publication will have it's own description of what "published" means.
Writing.Com does allow you to mark works private when posting them, or restricted to members of the site only, via the access restrictions setting when posting work to your portfolio. Those concerned about a piece being considered "previously published" would be advised to not leave their works as "public" in their portfolio, but instead restricted to at least "registered members and above".
Hope this helps,
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