1. Create a new SVG graph widget and add tons of data sets, problems etc and make it really slow. Slow enough that sliders in data sets (point size, for example) takes ~2-3 seconds to move.
2. Press "Add" to finally create the heavy widget. It appears that nothing happens after several seconds. Maybe you didn't press the button hard enough, so press it again. And wait. Still nothing is added to dashboard after 10 seconds? OK, maybe press "Add" again to be sure and then go make your self some tea and come back.
3. Observe that 3 identical widgets have been created.

It could be just slow because of JS or it could be validation and we are just waiting on PHP to respond. There should be some kind of layer of prevention. Maybe a disabled button and form with transparent loader on top of configuration form while adding of the widget is being processed. Maybe this could affect other widget in the future, so this is not really specific to SVG graph, but the whole dashboard.