Well, we know that the tallest spike in flower is P. Newberry Parfait "Picotee". The spike that hasn't blossomed yet is most likely the same as Newberry Parfait is well know for mulitple spikes. Now, the odd man out has to be a second plant, probably grown in so close that it appears to be all one plant. It might even have only one leaf. I have no idea what the name is. That's as far out on the limb as I'm going. If it were my plant I'd re-pot and find out what is going on.
Thanks for the pictures and post some more if you decide to look into the "root" of the problem.
Al