How many dyndns addresses on my router ??

[#1]

Hello,
I'm new here and have a short quick question: I'll get round to reading the instructions later   
Can I set up more than one dyndns address in my router ?
eg: first.dyndns.org ; second.dyndns.org, third.dyndns.org ?

[#2]

Looking at the full CLI manual it appears that might be possible.
What I'm struggling to understand is why you would need to?

[#3]

Thanks Jelv,
Page 212 looks like the one I need.  My router arrived today so I can now have a play with it..
As for the reason, well,  I am a compulsive  " fiddler "      , don't really need to, just want to...
Cheers..