Studio reproduction cels do not have a letter 
before the number. Here's a beautiful example of 
an unmarked studio reproduction (this one's from 
Gravitation), if you're interested: 
http://ekizo.mandarake.co.jp/auc_e/itemInfo.do?
itemId=03001396870100001

Also, I've never seen anything but a CG-based 
rilezu cel come with a douga, and this obviously 
isn't one of those.