I was gifted a box of keg stuff (sanke taps, towers, a few sigots, etc), and in the box there were three of these. What the heck is it? Its obviously a tap, but its threaded inside the collar, and the two tubes sticking down are odd.
That's a Hoff-Stevens tap. I haven't seen that type used in quite a while, but I guarantee you'll need it within a month of getting rid of it. You should hang on to it.
There were three in the box, and I don't ever use big kegs for anything (I use cornys all the time). I'll probably keep one because they look neat. Are they more popular out west? Nobody I showed this to around here has ever seen one.
You'll see them refered to twin-prop taps as well. Mostly see them in the older barrel shaped kegs. The ones without the handles that are an absolute B@#$% to move. I think most breweries either did away with the Hoff-Stevens or retrofitted the valves to fit standard Sanke couplers. Standardization saves dollars.