Both the flower and foliage look different than all the entries in our database and online info. This may just be a mismarked plant, in which case you could put it on the ID forum to see if you can get a correct ID or confirmation that there are purple flowered forms with different leaves (sounds like a stretch but who knows). It appears that the 'purpurea' in the name is referring to the leaves rather than the bloom. Is this at a nursery or botanical garden? If so, you could also check with the curator.