As I understand it, the Azure load balancer does not allow for two virtual IPs, with the same external port, pointing at the same bank of machines. Also, as I understand it, this is a functional requirement for Kubernetes, due to having one-IP-per-"service" (where "service" means something special in the scheme of Kubernetes).
Microsoft announced support for Kubernetes nearly a year ago, yet, both of the ways of running Kubernetes on Azure are broken, and fundamentally, it seems Azure can't support Kubernetes efficiently, with traffic load balanced in front of my service.
As far as I can tell, the only alternative is to not use Azure load balancer at all and I can manually route traffic into a node myself and configure Kubernetes to spread the traffic out. This is surely inferior to using Azure load balancer. It also demonstrates a rather large gap between Azure and Google Cloud. Google Cloud has a much more flexible (and yet, less confusing) model for load balancing and easily supports Kubernetes scenarios.