Hmm ... I'm not real familiar with Zinnia so my suggestion may not be correct. I didn't realize there were so many different types of Coreopsis. I googled and found these but I'm really bad about comparing photos:
It may be a new introduction. I've been seeing more and more threadleaf types of Coreopsis in pinks, but hadn't seen any broad leaved varieties till now. Can you contact the nurseryman for more info?
"...and don't think the garden loses its ecstasy in winter. It's quiet, but the roots are down there riotous." Rumi