I am going to show my ignorance here and ask if bullenianum is the species name and Berrak if you could divulge the particulars of this mix I would appreciate them. I am always looking for small orchids I can grow.
As much as it looks like appletonium (or wolterianum), bullenianunum comes from Borneo and has a beefier flower.
Cribb says that this complex is a mess with very similar plants:
all species status names circulating freely in cultivation for what is probably the same plant.
With a comparison of the incredible amount of variation Averyanov has documented for appletonium in Vietnam, I wouldn't be surprised that bullenianum would have a ton of variation throughout the south pacific.