In each view
public partial class View2 : UserControl, IRegionMemberLifetime, INavigationAware { public bool KeepAlive { get { return false; } }
This is your problem:
bool INavigationAware.IsNavigationTarget(NavigationContext navigationContext) => true;
If you want a new view to be created and added to your region each time you call RequestNavigate(), IsNavigationTarget() must return false instead of true.
RequestNavigate()
IsNavigationTarget()