Good news - your old license is automatically valid for RichDirt2 Standard Edition. Enjoy the new breakthrough style, the new wash style, the new street preset, the exclusive sill edge feature and the down slope mode (added to the up slope mode from RichDirt 1).
No you even do not need to run the license installer a second time.
There 4 possibilities:
Both plugins can be installed on the same computer. You are free to choose any point in time to convert a scene. The new plugin RichScene has bonus code that updates a full scene. RichScene bonus also works when you did -not- buy a license of RichScene.
RichDirt2 always runs for both V-Ray and mental ray. The second renderer is free. RichDirt2 exlusively runs on 64 bit. In case you still have a computer with 32 bit keep RichDirt1. RichDirt2 does run with Max 2011, 2012, 2013. A port to Max 2014 will be available soon. RichDirt1 is -not- ported to 2014, you have to upgrade to RichDirt2 for 2014 (as said above this is free for you). License per seats - RichDirt1 had been valid for 3 seats. RichDirt2 is valid for 1 seat. When using your old RichDirt1 licenses for RichDirt2 Standard the 3-seat-privilege is maintained, you can use it with 3 seats as before.