Apparently it's something new that just started this week. Rather then just having Shiba & Chuck anchor the entire 5 pm hour, They decide to split the newcast in half with Sibila & Chuck anchoring the first half and then Shiba & so far David anchoring the second half...lame if you ask me. Personally I hope it's just a placeholder until WNBC decides on a permanent replacement for Tom be it someone hired from the outside, or a promotion from within at which point Shiba & Tom's replacement will most likely anchor the entire 5 pm hour.