Ok it is not Anton Abel since I saw his hallmark inside an oval, and not the [A] [A] that you have there, very distinctive letters with a large space in-between....
Alfred Allina and Abraham Altendorf are two other names listed, and I believe there are more....
It gets difficult since there were so many silversmiths working in Vienna, which is where I am concentrating the search.
Hi, Separate ``A`` in a rectangle was used beside Diana head 1867 – 1872. After 1872 assay office letter was within the punch i.e. in front of Diana head. But separate assay office letter continued to be used on small and composite objects (e.g. legs and finials of sugar boxes, candlestick handles), proving that every part of composite object meets silver standard, sometimes struck twice. The use was inconsistent and not well documented. Take a look here: viewtopic.php?f=8&t=30954&p=77052&hilit=vienna+chamberstick#p77052 Regards
AA, I believe AG2012 to be right; regional assay office letter A punched twice for Wien/Vienna used 1867-1872. To distinguish the marks before and after 1872, the post-1872 hallmarks have the addition of an assay office letter for both large and small items.
Best,
Peter
Source; Hallmark Research Institute World Hallmarks-Vl.1-Europe