Uniqueness of Group IDs

[Len Morgan]

Now that Sarah solved my card name problems, I have a question about 
groups on stacks.

I don't want to print out the script of a group more than once if it's 
repeated on several cards.  My question is:

Is the group ID unique in a stack or could I have a group 1010 on one 
card and group 1010 on a different card that is a completely different 
group?  I know group IDs can be repeated in different stacks but I 
specifically concerned with group IDs in a single stack.

Thanks in advance,

len morgan