I don't see a problem with it as long as the wires are protected at their ampacity and all they need is single voltage circuits. Hopefully one of the insulated conductors is the "grounded" conductor and one is the "grounding" conductor. I see that combination sometimes when a contractor has to refeed an existing subpanel after relocating the Service to accomodate a room addition. If they can't get to the existing panel with SER they wil use the existing SE cable and convert the old panel to 120v. This means connecting both bus to the same side of the line. Kinda hookey and maybe wouldn't pass for new construction but it's safe IMHO. It does potentially put the system in an unbalanced state but one could compensate for this at the main service.
