I was recently informed (by one Res Agent, so take that for what it's worth) that CO had recently 'fine tuned' the EUA so that Elites of multiple status rankings would be treated as separate passengers even when on the same PRN. Apparently enough Golds travelling with Silvers, or Plats travelling with Golds or Silvers, didn't want to 'wait around' for the upgrade.

She also claimed that if you do NOT want to be EUA'd, then have your OP number removed from the PRN until you arrive at the airport.