Sounds like it, but I’m still interested in finding out how big a deal it is. A quick search shows that there have been cars found with duplicate VINs and making a container with the same serial number seems like pretty pedestrian crime in comparison. That is not to say that this is a crime, could just be plain old manufacturing mistakes and it’s also obvious that not all container management systems check for it (even if it did, unless both end up in the same registry it won’t matter anyway).