Thanks for the update.
Matt's right, P. lowii covers a very wide geographical range, and in it are many different types. I for one believe more identifiably different species will come from this variable group. If you look in my paph book you will see many of the types. Don't forget, just recently we have split P. richardianum and P lynniae from P. lowii; you should see some of the others I've seen....perhaps Olaf and others have, too.
Your plants appear to me to be the outcome of two of those types crossed with each other; they are very close but have quite different dorsal sepals and manner of spotting on the petal bases. If you are ever able to find more location/habitat data, I'd be interested in knowing it.
Incidentally, are ALL the stems smooth, fuzzy, or different? How would you describe them? And, how tall are they?