Yes, it looks like 2 different clematis to me also. It could be a seedling of Carnaby. My clematis are always producing lots of seedlings that pop up close to the parent plant. The seedlings take a year to germinate and then usually 3 more years to bloom, so that is why you never saw the blooms before. I usually let them grow until they flower. I keep the ones I like and give the rest away or compost them if they are not garden worthy. Seedlings may look nothing like the parent plant.

That is a very logical explanation flowerfan! Thanks so much. :o) I went back out and looked at it closer and even the leaves are a different color and different looking. The purple one is about done and Canrnaby is just getting going. I think I will leave it be because the bloom cycles are a little bit different. The trellis has a bit more interest this way.