I also would say double dig is clearly something different than just one throw. And at least double dig instead of throw would have done nothing with quite some items such as the spear for example. And by the way I usually even used items via the context menu(which would be context-throw (as that could be done while tumbling).
And as I mentioned in the dual-wield post of mine, you can try the only-key "throw" by playing this knueppeln stuff, where you release different spells on Q, E or R button respectively. A confusion there never occured to me, but confusing mouse throw and use happens regularily to me :-(