I think you do have a Phaius flavus. I don't know of any yellow Phaius tankervilleae.

Phaius tankervilleae tends to be a reddish-brown with a little bit of violet on the lip.

There is a purple Phaius species, though...Phaius mishmensis.

Phaius mishmensis - Orchids Wiki

I did attach some pics, both nun's are in the back corner, they look the same to me. She was stating over the phone when I told her there are no tags and I have no clue which one is which that one that is SHORTER is yellow, and the other one regular. Go figure, they look pretty same to me:-) Anyway, I was under the assumption that it is the same phaius, just different color, now when you mentioned it, I think I might have one flavus and one tankervilliae. Excited here:-) Totally new to this orchid group, so hope they will bloom soon for me to see and post pictures for you guys:-)

---------- Post added at 11:44 AM ---------- Previous post was at 11:40 AM ----------

One is definitely tankervilliae, as she described the color the same way like you did - reddish brown. Than, the other baby must be flavus, wow, see, I didn't even know that I have two different species, wow, this is exciting, thank you so much. Now I really can't wait for them to bloom:-)

I think the biggest difference between Phaius tankervilleae and Phaius flavus is the height of the pseudobulb.

The Phaius with the taller, more conical looking pseudobulbs are most likely Phaius tankervilleae. The Phaius with the smaller, shorter, more globular looking pseudobulbs are most likely Phaius flavus.