In this magazine (https://archive.org/details/openco…up?view=theater) I've found a picture of the cup that may raise more questions that it solves ! 
The faces of the skeletons, the tripod or the pig's back leg aren't the same as in most of the cups pictures ! It might have been restored or damadged but the tripod is really different in the magazine. If you can read Greek, this photo might help though.
