I’ve been under the impression there is no such thing as a duplicate content penalty.
That is, Google will not penalize duplicate content per se, it simply shows which one it considers “best” in the SERPs.
Depending on whether or not one SitePoint page or the other is the preferred, I guess it could be an issue. But IMHO as long as they link to each other i.e. “read more” ↔ “read comments” I don’t see there being a problem.