Some cards have a skull icon in their name but I missed the meaning of this icon in the rules. An example of this is 'Veteran Brother Maxos'. Is this skull icon meant to indicate that you can only have 1 copy of the specific card in your deck?

These are "unique cards" you can have up to 3 copies in your deck, but you can only have 1 in play at a time.

(you can not play, put into play or take control of a unique card if you already have a card in play with the same name)

Note that the bit about not being able to play, put into play or take control of a unique card if you already have a copy in play applies if you own OR control the copy that is already in play. So, for example, if you play a copy and the opponent takes control of it, you still can't play another.

Hi Slade,

In addition to the responses from Robin and ktom, the full explanation is available on page 16 of the RRG if you want/need to read it for yourself.