Unlikely, if only because it's actually not easy to do that. You'd have to get the container placed at the edge of the ship when in dock, then get the locks on

Unlikely, if only because it's actually not easy to do that. You'd have to get the container placed at the edge of the ship when in dock, then get the locks on the container undone while underway, then either hope that the container gets washed overboard in a storm, and doesn't hit the ship on its way out, or get a couple guys to lever it off. Which is totally doable, except that a container can weigh 30 tons, and you've got the space between rows of containers to use for working in. Admittedly, if it's at the top of the column, its probably a lighter container. But it's still going to be heavy, with the crew working up in the air, in a relatively narrow area.