Garret Dillahunt on Deadwood

So I just finished watching tonight’s Deadwood, and I knew I recognized the actor who played Mr. W on this episode. It took me until nearly the end until I realized where I knew him from, and then it came to me: it’s the same actor who played Jack McCall. It was his nose I recognized, being slightly porcine as it is. The eye threw me off, though, I admit.

Does this doubling have any plot significance? (Thematic doubling ala Shakespeare, right?) Or are they doing like Law & Order, where they just recycle actors?

I hope this is not a spoiler, otherwise I’m in trouble.