Another hand salute?

[Tib. Gabinius]

Hm, no.
Watch the details.
They both touch their heads / helmets. That similar, right.
The one above touch his helmet from "behind" which could be a tribute to the lacking place to show else. But he also touch his helmet on the top, looks like next to the crista.
The lower touch his helmet at the front edges, the hand is not higher than the face. He also opens his hand to the wachting, while the above lay down his hand flat on the helmet (which will cost him some attention to clean it ).

So, in the first moment, it looks similar, but a closer view brings new ideas.

Perhaps it's just like the military salute in the UK and in Germany, same thing in two variations, but perhaps it also mean something completly different, like some gestures today (spanish and french can sing a song of it).

[M. Demetrius]

Maybe their helmet liners made their scalps itch. ??

The tradition of fingers to brow, tipping of a hat, etc. is said to come from lifting a medieval visor to show the face...a recognition device, now used as respect or salutation to a superior military person, or government official.

The Romans didn't use visors, AFAIK, so that sort of salute doesn't relate to their era. Hard to say if those hands-to-helmet poses are salutes, IMHO. In the second instance, it's not clear which of the figures on the left would be the subject of the salute. None of them seem to be paying much attention to the soldier who is "saluting."

[Tarbicus]

Are we assuming too much that, to be a salute, the hand had to go to the front because that's what modern soldiers do? We should bear in mind that the gesture is to indicate removal of the helmet in deference to the gods, not to follow a drilled modern military routine.

[tommy303]

Removing one's helmet when in the presence of a god or his image in a shrine would be akin to going bareheaded into a church--a sign of humility and respect.

Removing ones helmet when going before a high superior, such as one's legate or tribune, proconsul, or emperor, would be the ultimate show of subservience as you are removing the one truly vital article of protection. The removal of the helmet would show your loyalty to him and your trust.

[Tarbicus]

Removing one's helmet when in the presence of a god or his image in a shrine would be akin to going bareheaded into a church--a sign of humility and respect.

Removing ones helmet when going before a high superior, such as one's legate or tribune, proconsul, or emperor, would be the ultimate show of subservience as you are removing the one truly vital article of protection. The removal of the helmet would show your loyalty to him and your trust.

That might not be how it was, if you read the thread. The head was covered while praying and paying homage to the gods. When hailing a mortal it was wise to uncover the head to avoid the danger that the gods would think that mortal was being held with the same esteem as them. So it's kind of the other way around, where the Roman practices were opposite to modern church ones.