There is a restriction under Solaris, a line in /etc/group shouldn't be longer than 512 characters. Consequently this limits the number of users in a group to a very small number. In order to lift this restriction, Solaris allows for multiple lines to be present in /etc/group for the same group.
f.i.
/etc/group

staff:1000:user1,user2,user3
staff:1000:user4,user5,user6

The problem is if you want to use this group in your sudoers file, f.i. grant all users in the group staff to shutdown the system. Only the users in the first line (user1,user2,user3) are allowed to execute the shutdown, all other lines are ignored.