Why are there 2 sets of cast members for the police in "Law & Order:CI"!

Question:

Why are there 2 sets of cast members for the police in "Law & Order:CI"?

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1 with Vincent D'Onofrio in the episode showing, the other has Chris North

Answers: vincent d'onofrio was hospitalised for exhaustion and the doctors ordered that he had to take a break, so the people behind the show organised for the other two agents to do the first half of last season, then goren and eames for the rest. I thought they fired the first two people and hired the new ones. I like the first two best I don't like the new actors. Chris Noth has been on the series on and off for a while... They have it set up like Law & Order:SVU- with Stabler and Benson as the main detectives, but Finch & Munch as supporting detectives....

I like all of the characters on CI :)

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