I found this Can an NS Record Point To Multiple A Records?, but wonders what is the difference, if any.

For example:

mydomain.com. IN NS ns1.myhost.com.
mydomain.com. IN NS ns2.myhost.com.

ns1.myhost.com. IN A 111.222.333.1
ns2.myhost.com. IN A 111.222.333.2

versus

mydomain.com. IN NS ns.myhost.com.

ns.myhost.com. IN A 111.222.333.1
ns.myhost.com. IN A 111.222.333.2

EDIT: actually, come to think of it, it could be said the same for MX records. Any breaking differences?

EDIT 2: then again, MX allow use of priority values so its a different case, in that one-ip-per-domain is more useful sometimes.