Are there any implications where an A records as a subdomain of a CNAME record would cause issues resolving.
For Example.
$TTL 3600
primary.www.example.com. IN A 10.0.0.10
secondary.www.example.com. IN A 10.0.0.10
www.example.com. 300 IN CNAME primary.www.example.com.
Not really, no.