I don't know how or why they got started but they were selling it under the 'Frequent Violet' name. (My guess is that maybe because they also sell 'Frequent Flyer', they wanted to link, by name, the rebloom qualities of this plant ("just like 'Frequent Flyer'!"), but differentiate the colors.) It sounds like when they tried selling it under the proper name, 'Rosalie Figge', the contractors/landscapers who purchase from them got confused, so it was in their best business interests to just keep using the 'Frequent Violet' name. Per my email inquiry:
"To answer your other questions: yes, our 'Frequent Violet' is the same plant as 'Rosalie Figge' but landscapers in our area had gotten used to our name. It got confusing enough that we just list it as 'Frequent Violet' in our catalog."
At least they put the "(R. Figge)" after the 'Frequent Violet' name, which led me to inquire about the plant's identity. If they hadn't, I probably would have purchased it thinking it was a different plant (I already have 'Rosalie Figge' on order from an iris specialty nursery). I do wish, if they insist on continuing to sell it under the 'Frequent Violet' name, that they would put a line in their catalog that would clarify this point - that its proper name is 'Rosalie Figge'.