Heather, listen to the Paphheads.
Jason, here's a closeup of my roebellinii. Note the long spirally petals. That is the only difference I see in our plants but the leaf is identical to mine and philippinese leaves are larger broader and more leather strap like than "succulent" and the tips are more rounded than a little pointed as in the roebellinii leaves. I'm not a taxonomist but these two species definitely look very different from each other. Actually, the shape of the pouches slightly differ, reobellinii pouches are smaller and a little pointed and philippinense pouches are more "helmet" shaped and larger. Also the staminodes in the roebellinii are smaller and narrower.