This mark is said to date back to around 1880. Until recently, this was little more than a guess, as most resellers had no idea what they were dealing with. In short, whatever resellers might tell you, this mark is not that old, nor is it a long-lost mark formerly used by a renowned factory. It has an ugly cousin, too!
Sure, one could assume that they both point towards an importer, distributor or retailer. However, neither of the two marks is referenced in any older material or publications on importers/distributors. Also, the terms/names used (Wallendar and Millar) do not make sense in German. Furthermore, the Millar mark raises a few red flags. If you're interested, take a look at the Millar Beyreuth mark listed as M180601.

M090602a
Castle/building seated upon a hill above a bridge. Text simply reads "WALLENDAR AUSTRIA".