Actually, it's not a design I've seen either, and it doesn't crop up in any of the catalogues from Holmegaard (or Kastrup) that I have (but I only have a few, so that doesn't mean too much).
The write-up does make it sound like it's an old favourite, though, but I suspect it might be just an old design never put into production, as with the 'New Wave' lamp designed by Verner Panton for Holmegaard in 1984 and only produced within the last 2-3 years.
I think this resurgence of old designs being dredged out of the archives is the glassworks' response to flagging sales over the last decade or two due to the wholly uninspiring new designs they've been releasing (usually with extortionate pricetags). See also their re-release of Lutken's 1955 'Canada' range.
I do really quite like these Bang vases, and I'm very tempted to buy one of each.