Check out the details. You'll find that this man is an ordinary miles, i.e. a legionary. He is equipped with two different pila but also has an oval shield, and apparently a flat one. Further, his armour is chain mail. Actually, there are a lot of sources which prove that many legionaries wore chain mail rather than the lorica segmentata (for instance, you could try and check out the pictorial sources referred to by the same website). As for the oval shield this may or may not have been an exception as Legio II Adiutrix was made up of former sailors, i.e. auxiliaries, and may have continued to use the flat oval shield associated with auxiliaries even after the creation of the legion (for some time, at least). But still, this is a legionary, and he's carrying his oval shield while being a legionary, not an auxiliary.