Renaissance cars just have couplers which are incompatible with the legacy fleet, unless you use „Baggage Transition“ cars. Therefore, the Siemens trainsets (and also the Renaissance trainsets in the Corridor) operate as „pure“ consists, whereas the Ocean is a mix of Renaissance and HEP-1 cars and the rest of the Corridor is indeed a happy mix of LRCs, HEP-1s and HEP-2s…
Except for the occasional anomaly like this:
Desperate times, desperate measures?