This is one of those cases where there are two hostas with the same name. Neither is registered with The American Hosta Society. The first one to be registered would become the "official" hosta of that name and the other would have to be renamed.

Originated by Dr. Jamison Harrison of Massachusetts, this non-registered cultivar is of unidentified parentage. It is a hosta with shiny, jade green colored foliage which bears lilac colored flowers in July.

Schmid lists this cultivar as H. 'Wunderbar'.

Hosta Helper will call this plant 'Wundebar' (Harrison)

An article by Warren I. Pollack in The Hosta Journal  (2020 Vol. 51 No. 1) titled Doppelgänger Hostas: Fancy Name for Look-alike Hostas, included a long list of hostas which various hostaphiles, published articles or other sources have indicated "look" the same. Some of these are, in fact, the same plant with two or more different names. Others are hostas that vary in some minor trait which is not immediately discernable to the casual observer such as seasonal color variations, bloom traits, ploidy, etc. So, as Warren mentions, hostaphiles may differ as to the plants listed but then, their opinions are based on visual observations and interpretations.

H. 'Royal Empress', H. 'Wu Hoo', H. 'Wu La La' and H. 'Wundebar'.

This non-registered cultivar is a sport of H. 'Empress Wu' from Marco and Joyce Fransen of Fransen Hostas in the Netherlands. It is a very large to giant size hosta with blue-green foliage and a wide yellow marginal variegation. From late June into July, very pale lavender flowers with faint striping bloom on scapes up to 4 feet tall. It sets viable seeds.

Hosta Helper will call this plant 'Wundebar' (Fransen)