thanks for replying 
If Darwin eats a little extra calcium dust, I don't think it should hurt him as long as he isn't getting too much vitamin D3 or UV or sunlight.
Since he is not eating much he is not getting too much vitD3. The only Ca/D3 is from the occasional dusted roach or cricket he eats. If anything I was think he was not getting enough and that's why he kept going for it - like a craving. He has one full length (4') UVB bulb and one 18" over his cool down spot. I just replaced them both yesterday (since July).
You said..."He is not growing - has not shed since Aug or Sept."...how close is he to adult size?
He will be one year in Feb. He began this semi-brumation at the end of the summer and I asked on both forums, spoke to a local beardie guy at the October herp show and my vet. I got mixed opinions: "force him to stay active - he is too young to brumate" and others who said they had younger bd's that brumated in their first year and were fine. From the bd forum there were several posts right around the same time of other keepers with the same situation. I got to the point in November that I was not going to fight nature and let him do what he wanted. His lights are only on for 10 hours (my vet said no less than 9), I offer him his salad and a variety of supers, roaches, crickets and baby food (apple/plum). Not all everyday
Today he ate an adult OH roach and one piece of kale. Tomorrow he will likely eat nothing. I'm not really worried as he has been holding at 362-364g and has had a recent clean fecal.
Does herptivite have preformed vitamin A?
it has beta carotene. I gutload his feeders really well so I rarely even dust with the herptivite. I cut back on the Ca as well since he was not growing, but when I would dust he'd lick the bowl, thus my thinking his body needed it - or he is just quirky 
(I kept beardies for over 10 years but when my last one died a year or two ago, I decided not to get any more. It was a hard decision since they are such neat creatures, but I have too many other creatures right now.)
Yeah, he is a sweetie, but I'll be happy when he is his perky, pretty self again! I assume he has some more grwoing to do - he's about 16.5" but we have a long winter up here in the northeast so it will be awhile!
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Chameleon Help & Resource Info
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skipper
0.1 Mad. Hissers and she is on the loose!
0.1 Chilean Rose Hair Tarantula - Rosa Leigh
0.1 Goliath Bird-Eater Tarantula - Natasha
?.? Pinktoe Tarantula - no name yet