It is chain aggro. Had to deal with this also when I started populating zones.
The emulator doesn't take walls into consideration yet.
Any mobs you're placing in a tightly packed hallway have to have super low aggro ranges. If you have an NPC right behind a door that the player is going to open and be suprised by the NPC, he has to have a super low aggro range, otherwise he'll see you before you get anywhere near the door and come charging at you warping through everything in his path (ruining the intended suprise, and leaving you with another less than exciting suprise).
If you're standing 85 units or less to an 85 aggro ranged NPC, no matter how many walls there are between you and that mob, he sees you. You, as a content creator, have to take the NPCs position, and any position the player might be in, into consideration while making your aggro ranges. Create the illusion that they can't see through walls by playing with their aggro ranges.
I created low and high aggro ranges of most NPCs I had created. If there was wide open area in the zone, the NPCs there would be the higher ranged ones. If I wanted those same type of NPCs inside a building, I'd start using the low aggro range ones instead. That way, when I go up to the door to the next room, the aggro ranges of the mobs inside do not extend out into the room that I'm currently in.
Some zones will require having high range, medium range, low range, and luuuuudicrously low aggro range NPCs, just so it all works out right. It all depends on the terrain, and where players could possibley be standing while they approach these NPCs.
You as the creator of content on your server, have to manipulate the NPC aggro ranges in such a way that it "appears" that they can not see you through the walls. Unless, or course, someone else creates this database first and puts it up for download heh

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