The arguments over what this image tells us about the rower positioning are on-going.
Many historians assert the three types were placed along each side of the ship at three levels bottom to top and superimposed over each other, but this configuration is problematic. Collisions between the oars were likely and the requirement for longer oars for oarsmen farther from the water sacrificed mechanical advantage because of the inefficient angle of attack.
Regarding multiple rowers per oar we take Thucydides word (Book 2, 93.2) that each rower during the Peloponnesian War used one oar.
That leaves us with the rowers seated next to each other as the remaining option. Let us look at some quotes from those who have made a contribution to solving the mystery.