The Dunstall name has been acquired by Burton Bike Bits in the same kind of way the Lucas and Hepolite names have been acquired by Wassell. Which means those discs have as much connection with Dunstall as the aforesaid two other brands do with the names they're sold under.
BBB is one of a small handful of retailers I'll never use again, after having been sent inferior parts, clearly different to what I specifically asked for and checked on the phone that they would be what I was looking for, and then excused themselves by saying they didn't have any in stock so sent what they sent (without any kind of explanation, nor a reduction in price despite the inferior parts being a lot cheaper). Yes, they refunded me (rather reluctantly), but any dealer who operates like that won't get my custom or recommendation.