I think an answer can be inferred from the Aruch Hashulchan's detailed discussion in 673:9-12. He sources the Tur, who says explicitly that there are two non-mitzva lights in addition to the official Chanuka lights. One is a "helper light" called the shamash and the other is an "extra" one.
The shamash is used to light the other light(s). In practice this one must be lit first. As the general principle of saying brachos over la'asiyas mitzvos (i.e. immediately before performance) applies here, I would assume that the b'rachos would be recited in between the shamash and the real lights.
The extra light serves the purpose of ensuring that the increased visibility in the room is attributable to a non-mitzva source and therefore usable. The Tur clearly says that this light is lit after¹ the mitzva light(s) and is not called a shamash.
The two primary transmitters of the Tur's words - Rav Yosef Karo and Rav Moshe Iserles disagree about how to differentiate this light from the others, but it does seem that they conflate it functionally with the shamash, resulting in only one candle. The Aruch Hashulchan concludes by recommending satisfying all aforementioned opinions by using a shamash and then leaving it near to but distinctively from the other light(s).
¹It does appear interestingly that it should be the last one lit so that the official lights are physically grouped together but that designating one of the middle lights as the extra one might not invalidate anything.