I ran out to my new double ruds to answer your question for both of us! My double ruds have seeds similar to regular ruds, but there don't seem to be as many in one seed head as in regular rudbeckia.

Basically they are the little gray/black pegs that are shorter than the spikes on the head.

Is the ligher color parts just chaff? I can't seperate the light from the dark, so if I'm going to trade seed, is this OK to leave with the black pegs?

Here's my theory, communication is key. Personally, I don't have the time or patience to seperate chaff from seed on rudbeckias. It's just too tedious. So, I trade my ruds with chaff. I try and eliminate most of it and make sure there is plenty of seed in each envelope.

I have winter sowed a gazillion ruds and so far, the chaff with the seed has never been a problem. Seems to me that as long as you make it clear that there is going to be chaff and that you make sure there is plenty of seed, the traders can decide if it's the trade for them. Just be honest and do your best.

I like this idea the best. I will not spend hours trying to seperate the chaff. Thanks for the tip!