OK, from reading the thread title, I know you're already thinking "Duh - 1 of each!"
BUT
Here's where RAI vs RAW _really_ breaks down.
Take a GOOD look at page 128 in C:SM. That's the page that breaks down an army list entry.
Now pay good attention to parts 2 & 3. That's Unit Composition and Unit Type.
Then compare that to some of the named characters in the army list. Those observant types out there should by now have noticed a discrepancy. It's this:
Unit TYPE has rules for Unique units. saying "If the Unit Type box includes the word 'Unique', you may only include one of this unit in your army."
Unit entries, however, place the word Unique in the Unit Composition, which has no bearing on how many you can take per army (there's no ruling for "Unique" under the Unit Composition definition).
Note also this has not been Errata'd or FAQ'd on the GW website.
OK, I don't play Marines (Well, Space Wolves, but we run from a different, unaffected, Codex, for now), so I'm not going to pull a fast one with this. But it's food for thought for the hardcore tourney boys out there. And one I feel has an arguable ground, too. Granted, it's easy enough to say "No, not playing you" in a pick-up store game, but if you HAVE to play against that, in a tourney?
Have at it, guys (and gals).....
Footnote:
This seems to be C:SM specific. The recent pre-5th ed Codices, and C:IG, either have the "Unique" ruling/rule in the right place, or use other methods to show uniqueness (eg, C:CSM states that "all units on these two pages are unique and may only be taken once per army. eg, No two Abadons. (or something to that effect))