Older source

The June 1963 issue of Famous Monsters of Filmland, available as of writing on archive.org, features a lengthy article about different stage and screen versions of Dracula. On page 43, we get the following sentence with no further elaboration:

"Eric Jason, specialist in stage monsters, once told me he was sure there'd been a Russian version of DRACULA."

Hardly any better evidence than what's been posted here before, but might be a good candidate for where the rumours began. If I had to guess, I'd say somebody saw this reference after having stumbled upon an article about the, then still mostly unknown, Drakula halála (which, according to research by Gary D. Rhodes, went into production in 1920 under the working title of simply 'Drakula') and conflated the two together in their head. Though this is all, admittedly, just wild theorising on my part.