I see the object as a compound symbol; ank, key and Mercury.
Gemini (ruled by Mercury) was a twin, one, at first, mortal and the other immortal ... also Mercury is lord of the heavens and the underworld and able to travel, bring people and communicate between them.
As far as the GD / Budge double Anubis goes ( and as it points out - actually 1 God with a double function ) I would recommend Normandy Ellis' wonderful transliterations of the Egyptian Pyramid texts where she talks about (transliterates the original, in the first person) the woman's spirit crossing the great desert after her death. A jackal is seen approaching from the distance ... it isnt too friendly and seems to be a leader of an unseen pack (one type of 'severe' jackal). It eventually comes up to he and sniffs her and calls out to the others (Wepwawet's other function as a 'scout') "It is all right, she is one of us."(the 'other type' - more merciful ) and then leads her through the next stage of the afterlife. (The severity of mercy of the approach was due to the woman being able to truthfully recite the 'negative confession' previously at an earlier stage of her death journey .... otherwise - jackal food! )
So they are the guardians of the threshold (as well as' Lord of Transformation' ) and they hold the Mercurial powers and the keys to life and death.
[ There is a theory that the ank evolved from a symbol much like a more modern Ashanti fertility doll , in their stylised versions you can see the similarity, these symbols were also seen as representing a power of regeneration and fertility. The birth of new life. ]
Now, all you have to do is find the 'key' ..... and make sure you have the right smell
All this can then be looked at in contexts of the unconscious and Pisces ( 2 fish, one swimming one way, another the opposite way
)
{ Since this early 'understanding' of 'post Victorian ' Egyptology' , much research has been done and the modern view is different from the above ... but here - in Crowley's tarot and other related subjects like GD and Freemason's ceremony , Egyptian symbolism is quiet dated and often wrong (or comes from the New Kingdom where such 'amalgamations were already under way) ... we have to see it, in this case, as 'Thelemo-Egyptology'. Eg. a more modern approach is that Anpu and Wepwawet were very different gods with different origins and locations. }