Luc quite rightly pointed out that redistribution 'as is' would be contravening the Verisign agreement. However, if it's modified like I want it (i.e. just the deduped domain names) then as I read the agreement, that's OK as it's an 'enhancement' of the original files, but NOT the original files themselves. I also do NOT need the TTL and DNS data.
Yes, I guess I could just complete the Verisign agreement but I think it takes ages and I'd just be happy to pay for what I want.
Thanks!