As one of Vuo's developers, I work on Vuo's engine (the thing that makes compositions run), work on nodes, and write documentation. You'll see me on the forums answering people's questions about Vuo.
I've been developing apps and frameworks for several years (since I was in college). Pre-Vuo projects include Kineme Quartz Composer plugins, iOS apps for education, an app that analyzes photographs of tomato slices, and software to help people with disabilities use talking keyboards.
I enjoy using Vuo to make live music visuals. My hope for Vuo is that it will grow into a community of people of diverse backgrounds and identities making lots of different artistic, useful, unique, goofy, beautiful, crafty, wonderful compositions.
Your system seems to have multiple local network interfaces (192.168.* and 172.*). That might be because it has both wifi and wired ethernet connected at the same time, or because you're connected to a VPN, or have a VM running, or because you have Thunderbolt or Firewire or Bluetooth or USB networking enabled, or something. Under System Preferences > Network, all the green dots are active network interfaces.
Vuo 1.2.6's OSC Broadcast mode (Make OSC Output) sends to all the network interfaces, to improve the chance of the message getting through to where you want it. If the receiving end is also listening on each of the multiple network interfaces, then it will receive the OSC message on each of those interfaces.
So the correct setup, as you figured out, would be to use Make OSC IP Output, which will only send to a single network interface.
Yep, we've made some improvements, including an option to specify the type of barcode. If you'd like to send some of those student barcodes privately (https://vuo.org/contact), we can see if that fixes your problem. And/or I can let you know if we publish an alpha/beta release of Vuo 1.3 so you can test yourself.
Those are good questions. I'm sure that making it built-in to Vuo would count as commercial since Vuo is a commercial product, but I'm unsure of all the implications of a node developed by a third party. If you happen to find anything in the OpenPose license agreement or other documentation that clears this up, please follow up here.