Yay, Pantone have upgraded Hueyto suit dual monitors. I’ve been testing it for a month now and it’s excellent.
Link to the upgrade purchase $39.99 US http://www.pantone.com/pages/products/product.aspx?pid=569&ca=2
You must register at myPantone before you can purchase.

I was frustrated to discover the upgrade couldn’t be purchased in Australia. The resellers here only wanted to sell me the whole package again, and I already have a Huey.
I queried the Pantone helpdesk and they told me to ‘fakeout’ the system and pretend I was a North American resident so I could download the upgrade.