When creating web maps in ArcGIS Online, often I tailor a layer (popups, filter, symbology, scale range) and need a duplicate it to maintain the same primary comfig, but with a different filter and scale range. Saving item properties (which is great for setting layers' defaults) isnt an option else I overwride my defaults. Add duplicate layer function to web map layers, adding a copy of that layer to the map with the same properties as the layer duplicated, not the default properties.
