Double breasted or center fastening?

[rocktupac]

Only,this raised chest cover can be achieved also with overlapping. The belly part would be double and the chest would only be one layer

I agree that it can be done that way, but it clearly is not being done that way in the image I posted. As to Patroclus, his armor is far different. The scallop at the neck is needed because the central portion is too high without it, cutting into the neck. The high front is quite clear on that vase, as is the fact that it is one layer showing.

There are images that don't show the raised front, but usually they are poor quality renders. One example of a good artist appearing to make this mistake is the famous Douris arming scene. The fellow who appears to be fastening the tube in front also lacks a high front while the other images on the same vase all have ornate upper chest sections.

I'm pretty sure I know which vase you're talking about, and it does seem like the warrior dressing has a center-fastening cuirass. But, as you say, the others have a high chest while the warrior dressing does not, leading one to believe that the artist has made an error. The depiction of the armor in the first image you posted was clearly messed up by the artist; in reality, this cuirass would have abnormally long shoulder flaps and pteruges that ended somewhere around the belly button. The proportions are horribly portrayed.

There is another painting that shows a warrior dressing in what appears to be another center-fastening cuirass, this time the center is raised higher and clearly wraps up around the arms.