I don't know this particular router UI I think, but from the looks of it, I'd guess that you are forwarding from router:80 to 192.168.1.88:5001 and from router:81 to 192.168.1.88:5002. Which doesn't sounds like you are forwarding to individual haproxy instances in front of both OctoPrint and your webcam server(s) but rather individual OctoPrint instances.
What I'd rather suggest is either configuring haproxy with prefix URLs so that you can do something like /tevo to reach the Tevo and /tronxy to reach the TronXY and their individual webcams (via a forward router:80 to 192.168.1.88:80). Or alternatively configure a second haproxy instance on the machine running both OctoPrint instances, listening on e.g. port 81 instead of 80 and having your router forwards be of the form router:80 -> 192.168.1.88:80 and router:81 -> 192.168.1.88:81.
In any case, you won't be able to get remote webcam viewing to run at all unless you put a reverse proxy in front of both OctoPrint and the webcam server which is why OctoPi comes configured this way (btw, for two OctoPi instances, router:80 -> 192.168.1.88:80 and router:81 -> 192.168.1.89:80 would work out of the box).