Many sanderianum had the white margin on the leaves in the 90's indeed. There are a few colonies that don't, but back then it was the standard. They were collected in the Mulu Park, but the access was much more difficult by foot than what it became around 1998, where other colonies became readily accessible, including using helicopters...
For the flowers, this looks really like one of the old 90's sanderianum indeed. They were 100% wild collected back then, no seedlings were available. The Orchid Zone 'Deep Pockets' x 'Jacob's Ladder' thousands of released seedlings, that turned out to be PEOY, deterred most from doing their own seedlings...
Sanderianum has many types of plants and flowers, a bit like rothschildianum. Very narrow leaves, borderline looking like an esquirolei plant, very wide soft leaves, huge plants the size of a gigantifolium, tiny things of 25-30cm leafspan. They all existed back then.
Some were incredibly hard to grow, apparently it was really related to the colonies they came from. Today, what persists worldwide is bred from maybe 20 wild original plants, not even.
