I just spent the morning ordering from Silver Star Vinery
The owner is very helpful, and the site has very good descriptions and explanations of clematis, and bloom times, how to prune, etc.

I am really surprised no one has posted from your zone to help answer this question. I know for me in a zone 4, the early bloomers that usually bloom twice, on old wood and new wood, only bloom once due to the stems being winter killed but the type 3 hard prune types will bloom twice if they are cut back after the first bloom. None of mine start blooming until July. I hope others will post that are in your zone to help answer your question. Mikelite, a new one that I got from Silver Star actually bloomed twice for me last year and that was when I planted it. I have never had a clematis bloom twice the same year I plant it in this short growing zone I am in so that told me it is a strong grower and I ordered 2 more this year.