As I do not expect any response on Stackoverflow (.net - Strange effect it seems arcgis (10.2.3) shows tiles of multiple zoom levels - Stack Overflow), I wanted to try it here.
I have to layers one base layer and an overlay layer with transparent tiles containing only seamarks, My XAML looks like that:
<esri:MapView x:Name="MyMapView" Grid.ColumnSpan="2" Margin="0,0,10,0" DragEnter="MyMapView_DragEnter" DragLeave="MyMapView_DragLeave" MouseDoubleClick="MyMapView_MouseDoubleClick" MouseLeftButtonDown="MyMapView_MouseLeftButtonDown" MouseLeftButtonUp="MyMapView_MouseLeftButtonUp" MouseMove="MyMapView_MouseMove">
<esri:Map x:Name="MyMap" >
<esri:ArcGISTiledMapServiceLayer ID="BaseMap"
ServiceUri="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
<esri:OpenStreetMapLayer ID="SeamarkMap" DisplayName="SeamarkMap" TemplateUri="http://tiles.openseamap.org/seamark/{level}/{col}/{row}.png" />
</esri:Map>
</esri:MapView>
All maks of the SeamarkMap-Layer are rendered but if I zoom in, Images like the attatched one come out. It seems like on a layer Tiles of different zoom levels and scale remain visible. Did I a configuration mistake or is it a Bug?