Unfortunately I have no idea. There are dozens and dozens of Vanda hybrids out there that produce purple flowers.
It could be a Dr. Anek, a Gordon Dillon or any number of things. It could be a hybrid of Gordon Dillon. It would be next to impossible to say with any degree of certainty. You could even find one or two that seem to be close but there is no way to be sure.
This is exactly why I don't buy plants without a tag. Even with a tag, it doesn't guarantee anything but it makes me more comfortable.
