Find in \conf\char_athena.conf
start_point: iz_int,18,26:iz_int01,18,26:iz_int02,18,26:iz_int03,18,26:iz_int04,18,26
Change to:
start_point: iz_int,18,26
If you want. you can go further and remove duplicate NPCs from:
\npc\re\jobs\novice\academy.txt
\npc\re\cities\izlude.txt
\npc\re\quests\quests_izlude.txt
\npc\re\warps\cities\izlude.txt