You can and many skaters actually did even the last year, esp. from federations who don't have many competitive skaters (Eva Lotta Kiibus, Alexandra Feigin and others). Just competing in junior and senior GP during the same season isn't allowed. The other problem is that it is pretty close and it can be difficult to have two top competitions back to back. That's why there were talks about whether Artur Danielian will attend junior worlds or not for instance.
And besides Kurakova and Tornaghi, Ryabova and Urushadze will be at Junior Worlds as well. I expect all these girls to be at Senior Worlds, it will be interesting to see how they can cope with two major championships so close to each other.

I am sure You-know-who already has a ruler and a scope ready to measure angle of edge and 'pre rotation' size