It can be confusing. There's a 'Rough Comfrey' that is very very similar to both Russian and True Comfrey. Las year ours had dark pink flowers too.
When you're splitting comfrey, a piece of root smaller that your little fingernail will grow into a small plant. Thats how it spreads as well. Once you've got it, you'll pretty well have it for ever.
Thanks for the reply. Makes me wonder if maybe some of these plants were just too small to notice last year.