Kim,
I don't know what you mean by "markings". If it is blue big spot - I deliberately exaggerate of course- it doesn't match with denisoniana.
I have quite a few photos of denisoniana from my own collection or that I have taken during shows and undeniably there are forms/varieties of denisoniana who have marks or even tessellation. David Grove notes in his book about Vanda that "some varieties have spots, short bars or tessellation" and Martin Motes writes that denisoniana "in (some) forms, these spots are quite obvious : they are, for example, large and prominent in the variety hebraica."
But both Grove and Motes states "it might be an unsatisfactory" solution and that the case "presents many unresolved taxonomic problems" (Motes).
Anyway, I know that Motes, Roberts and Gardiner are currently working on these denisoniana forms/varieties : we should have more reliable informations soon.
Here are some different examples of denisoniana with light to heavy markings/tessellation :