I wrote a topic on this recently
Cookbook: Multiple Dashboards on the same server, with IIS - PowerShell Universal - Ironman Software Forums
There are some caveats of course, mentioned in there.
Edit: I see you run 2.6.0 Be aware that there are issues with 2.6.0 and possibly 2.6.1 with IIS.
I have a single server running 6 instances 2.5.5, for testing purposes, works great!