Dear Rabbi I just inherited a lovely brass chanukkiah. It’s a bit strange looking. It has TWO shamash-candle holders. The lamp is in the shape of a small throne with the nine candle-holders in the seat.There is a back with lions of judah, two birds, pommegranates and Jachin and Boaz. On the arm-rests there are two additional birs and one shamash-holder on each arm rest... I was told years ago that this was common in ancient times. What’s the story of the TWO shamashim? Is it even a chanukkiah?
Chanukiya with two Shamashim is a common phenomenon as you mentioned, the origin is not that clear. Some reason it to be because of the holiness and sanctity of the Shamash so we therefore light an extra candle throughout Chanukah to actually use its light. Some explain the extra Shamash it to be use on Shabbat, either the Shabbat of Chanukah or of year round.