SOA and trailing dot

[Johnny Fribert Lauridsen]

Got this SOA via ls -d in nslookup - the DNS server is an MS DNS on NT:

xxx.dk.                       SOA    abc.xxx.dk . (132 3600 300 172800 7200)
  xxx.dk.                       NS     abc  

stuff here from the DNS server and then at the end of the listing:

  xxx.dk.                       SOA    abc.xxx.dk . (132 3600 300 172800 7200)

                       

1. What is the significant thing about not having the trailing dot '.' on the abc.xxx.dk in the SOA?
2. Also, is it fully valid to only have a dot for the contact info? 
3. The SOA is listed twice.  Is this significant, and why/how?

Note that this is a perfectly well working DNS server.

Thanks,
Johnny