How do I get my second "CNAME"?The Publishing wizard does not, always, provide instructions for ownership verification - and some owners don't understand that ownership verification is only necessary when it's demanded.
When ownership verification was first introduced, whenever a blog owner would use the Publishing wizard, to publish or re publish to any non BlogSpot URL, every use of the wizard would involve creating a new ownership verification "CNAME".
The ownership verification "certificate" is unique to both the URL being published, and the time the publishing takes place. If the owner waited too long between publishing attempts, a new "CNAME" would be again demanded. If multiple hosts were published in a domain, multiple "CNAME"s were required.
In some cases, each domain address being added would require at least 2 "CNAME"s - the DNS address for the published host ("ghs.google.com"), and the ownership verification (the long, random text). Domains with multiple hosts would end up with multiple, redundant, and useless ownership verification "CNAME"s.
Later, Blogger changed the requirement, so only one verification was required, for the domain.
Each domain now has an ownership verification indicator, invisible to us. If ownership is verified once, that is generally enough. When you publish to a domain URL, either a verification "CNAME" Is required, or it is not required.
In some cases, trying to Publish to a domain URL, with bogus base DNS addresses, will generate another infamous "bX" code - or the blog will seem to publish, but may be offline when accessed. Upon correction of the problem, with righteous DNS addresses setup, the Publishing wizard will simply publish, and the domain will be operational.
In either case, no second "CNAME" will be required. When the domain is operational, you wait for domain propagation (formerly called "Transition") to complete. While waiting, you continue the migration.
When the migration process is complete, you get on with publishing the blog.
If it should be necessary to re publish to the same host, or publish to a different host, in the domain - and ownership verification is required, instructions for adding a new "CNAME" will be provided. When the new "CNAME" Is needed, the new verification address (again, sensitive to domain address and to time of request) will be displayed in the Publishing wizard.
If ownership verification is not required, and the domain becomes operational when the Publishing wizard is used, you are done.
Some owners will use Google Webmaster Tools, and manually generate an ownership verification. This will give you specifications for a "CNAME" / "TXT" that is unnecessary now - and later, will be out of date. And, if your domain zone edit file is limited in size, this will unnecessarily limit the number of hosts you can add.
Helpful instructions by Blogger not withstanding, you need to add righteous DNS addresses, and get the domain working.
If ownership verification is required, add the required "CNAME". If ownership verification is not required, finish the domain migration, then get on with publishing the blog.