Time-honoured tradition in the horror world. The aforementioned Ramsey Campbell has his own Mythos. There are probably as many Mythoses as there are Mythos writers. And that is pretty much how he liked it. During Lovecraft's own lifetime, authors like Clark Ashton Smith, Robert E. Howard and even a young Robert Bloch added their takes on the Mythos, some of which HPL then incorporated into his own stories.He's developed his own mythos, and the podcasts are blending that with the Lovecraft one.