This practice varies depending on the court and/or judge's own style preferences and is often a judgment call based on what the author is trying to communicate with a citation.
I'll give a few reasons why a judgment might provide multiple layers of citations:
- because the "deeper" source is a well-used precedent for a particular point, so it is meaningful for readers to know that the shallower source cited the well-accepted leading case on an issue
- to show that a particular proposition has been long-accepted in a jurisdiction (your example might show that whatever proposition that is being cited has been used in this district over a 25-year period)
- to show that a decision from a lower-level court is consistent with historical jurisprudence or with higher-level jurisprudence
 It is common ground between the parties that reasonableness is the applicable standard of review for the Independent Chairperson’s decision. I agree (Perron v Canada (Attorney General), 2020 FC 741 ("Perron") at para 45, citing Canada (Minister of Citizenship and Immigration) v Vavilov, 2019 SCC 65 ("Vavilov") at para 23; see also Schmit v Canada (Attorney General), 2016 FC 1293 at paras 19-20, and the cases cited therein).
Here, the author is trying to say this point is well settled. What is the standard of review for decisions of the Independent Chairperson? It is "reasonableness." This was stated in Perron, which itself cited Vavilov, Canada's leading case (since 2019) on how to select the standard of review. It is important to know that Perron relied on Vavilov rather than an obsolete framework for selecting the standard of review.
In your particular example, it seems that Albert E. Price, Inc. v. Metzner is or was a leading case in the 3rd Circuit on what constitues irreparable harm when seeking a preliminary injunction in copyright infringment cases (based on my very brief skim of how other judgments tend to use it). By noting that a judgment cited Metzner, this is a form of shorthand that is quite meaningful to practitioners in this area of law.