I'm not normally one to jump on post-production materials, but since Kino's Journey is my favorite series and just so happens to be a digital production, I couldn't resist purchasing a rilezu from the series.
I'm fairly new to collecting, and I don't know very much about rilezus or post-production art in general. I have a few questions that I'm hoping some of you more experienced collectors can shed some light on.

Is each rilezu one-of-a-kind, or are multiples of the same image produced?
Also, I noticed that the rilezu I bought comes with a sketch. Is this the sketch used to create the rilezu, or is it the actual douga that was used in the production of the show? The sketch is somewhat different from the rilezu (sorry that I don't have pictures at the moment), so I'm thinking that it was used in the production? Is it a common practice to include the original production douga with the rilezu?
I realize that this may be hard to answer, but how rare are these things?
I also realize that some of these questions may be bit open-ended (as the circumstances for post-production material must vary from show-to-show) but any information would be appreciated. I'll post pictures of the cel in my RS gallery when it arrives, probably in 1-2 weeks.

Thanks for your help!
