Odd SCOTUS Couples (and Trios)

Adam Feldman in Empirical SCOTUS wrote Odd Couples (and Trios). He tracks unusual combinations of justices in dissents this term. E.g.,

Now for one of the really intriguing combinations. In Bank Markazi v. Peterson, Justice Roberts wrote a dissenting opinion which Justice Sotomayor joined. This is a first for this combination that do not often align in their perspectives. In this case we do not see simultaneous dissents, but a single dissent where the two Justices agree in the rationale.

We see the favor repaid in Ocasio v. United States where Justices Roberts, Thomas, and Sotomayor dissented. Justice Thomas wrote one dissent, while Justice Sotomayor wrote a dissenting opinion that Chief Justice Roberts joined. For two Justices that so infrequently agree in dissent, these two cases present a possibility for a burgeoning voting relationship.

I wish he went into the rationales in the cases. Is there a legal principle that these two agree on? I'm also bothered by the use of "quite unique" but that's just me.