Two "Blue"

Two years ago, Esposito had played a snitch who died a violent death. Similarly, Reni Santoni (Poppy on “Seinfeld”) made his first guest appearance as a detective working with Jimmy Smits, and later as a handyman who accidentally kills his buddy. And Julie Ariola has played a kleptomaniac cleaning lady, an attorney for Kim Delaney’s mother and an abused wife in past “Blue” episodes.

Producer Bochco has been an advocate for recycling — actors, not soda cans — since his first hit series, “Hill Street Blues,” in 1981. Dennis Franz had a short-term role on that show as Detective Sal Benedetto, only to reappear three seasons later as a regular, Lieutenant Norman Buntz. (“NYPD Blue” is Franz’s fourth Bochco series.) And “Blue”‘s James McDaniel (Lieutenant Fancy) was one of the stars of the ill-fated “Cop Rock.”

Esposito admits that some viewers may be confused by “Blue”‘s casting deja vu, but most seem to shake off their case of double vision. “After the second episode, a few people called me and said, ‘Was that the same person you played before?’,” he recalls. “But audiences are getting more savvy. They tend to say, ‘Wow, this guy is really convincing,’ and they don’t really think, ‘Oh, it’s the same thing as before.'”

Fans searching for secret relevance to “Blue”‘s repeated bookings might be disappointed at the straightforward motivation. “We just use people that we like,” says Junie Lowry-Johnson, the casting agent for the series, who has worked with Bochco since “Cop Rock” in 1990. “In the casting process, it can get very discouraging trying to find new people who stand out, because so few do.”