Ok, at present we only support one configuration per ad provider. This is a limitation of the V1 framework and we are looking to remove that impediment in V2 along with a host of other features.
The properties are static because that's how XAML declares dependency properties, if you are trying to have two instances of AdRotator running on the same page it should still work (but currently untested)
I'll do some investigation to see how we can support multiple instances on the same page.
If you are using multiple pubcenter APPID's or pub id's then we currently recommend to host your configuration XML on a free hosting service like Azure websites or AppHarbour and swap out ID's in the file remotely. not an ideal solution but
until V2 it's the only workable way at present.