I asked Dwight about this very matter.  Here is part of the official response, but I paraphrased it because they recommend against copy and paste:

The second furnace delivery date was moved from late 2012 to Q1 of 2013 at LCM's direction, as we noted in the November 26, 2012 Corporate Update.

Primary reason:  Focus on the testing of the first furnace, as has been done.  Follow up with commercial shipments to customers before receiving, installing and commissioning the second furnace.