Q. How can I configure multiple Web Application Proxy servers to publish the same applications in a redundant configuration?
A. Web Application Proxy (WAP), which is part of Windows Server 2012 R2, uses a consolidated configuration that is part of the ADFS deployment it is connected to. Therefore, if multiple WAP servers are using the same ADFS deployment then they will have the same published applications/services. There is no further action required.
If you need a global capability such as failover between locations for published application you could pair WAP with a global DNS resolution service that is geographically aware, for example Azure Traffic Manager. With this scenario, WAP in multiple locations would all be publishing the same services but users would be redirected to the WAP instance closest to them when using the Performance load balancing option of Traffic Manager.