[http://sourceforge.net/p/ufoai/bugs/2262 Item 2262] imported from sourceforge.net tracker on 2013-01-28 19:26:38

See attached screenshot. I am not 100% sure but I think both aliens spawned on the same tile. Maybe some debug code for printing/logging current alien position would be helpfull.
If this may help, screenshot is taken at:
2010/01/03 13:32:38 CM_LoadMap: "-industrial/ +craft_drop_firebird +craft_ufo_harvester +fr06_3x2 +fr12_3x3 +fr16_5x1 +fr13_2x1 +fr07 +fr14_1x3 +fr15_2x1 +fr08 +fr11_1x2 +fr05 +fr09 +fr01 +fr02" "8 16 0 0 -32 0 -16 0 0 -24 -32 0 -8 24 0 8 8 0 24 8 0 -24 -8 0 -16 -8 0 0 -8 0 -24 16 0 -16 24 0 -16 16 0 -8 16 0 0 16 0"
===== Comments Ported from Sourceforge =====

====== voovoos (2010-01-03 13:01:37) ======

two tamans on the same maptile inside harvester
====== voovoos (2010-01-03 13:13:44) ======

In this savegame go to the only geoscape mission. Almost always two tamans on one tile inside harvester (upper level).
====== aduke1 (2010-01-03 15:45:45) ======

I checked the harvester map in radiant. At least it's not a duplicate spawn point.

IIRC there is a command to 'unhide' all aliens on the battlescape. Using that cmd immediately after mapload you could find out if they are spawned in that cell.
====== aduke1 (2010-01-04 15:45:03) ======

I guess my memory didn't serve me well this time. Maybe it was just a user *requesting* such a cmd in the context of 'can't find last alien'.

But there is another way to find out: If we set g_notu 1 and walk to the point in question, we should also see the aliens as they were spawned.

I tried that a couple of times, but had no luck. One time the point was completely empty, the other times the passages were blocked by aliens. Btw I never got tamans, only ortnoks.
====== aduke1 (2010-01-04 16:33:11) ======

I noticed something important: the two tamans on the pic are NOT standing on the spawnpoint.
==> they must have walked there.
Did you use coded or LUA AI ?

If the dropship is in front of the harvester, the upper aliens have a tendency to gather in the cockpit. I checked the place several times after 1 and 2 turns, but never caught two aliens in one spot.

====== voovoos (2010-01-04 18:35:13) ======

Standard AI, no LUA. Interesting thing is that I repeated that map several times (was testing some code I've played with [1]) and I saw that double Tamans at that upper level of Harvester at least three times.

[1] no, my code had nothing to do with it, my code was inventory-related and only client-sided.
====== voovoos (2010-01-04 18:41:37) ======

Also, after searching IRClogs, found this at 23th November 2009:

19:39 < @geever > mattn, two Tamans were staying in the verysame cell :S

Unfortunately I don&#039;t see (in logs) any additional info, not even a mapname; it was before r27152 (for the record).
====== ralgert (2010-01-06 23:22:35) ======

I have upload an additional picture at imagehost, because i can&#039;t add any file.
http://f.imagehost.org/0738/2925207_ufo07.jpg

This is an old bug. There are exist any different bug entries for this theme. Sometimes, a Alien trapped in the same place from an another Alien.
I believe, this is a problem by the pathfinding (calculate empty place at a certain moment). Unfortunately i can&#039;t force the exact bug twice in a scenario.

If needed, i have save the log file (20100106_ufoconsole.log).

R27699
====== tlh2000 (2010-01-07 07:50:52) ======


====== tlh2000 (2010-01-07 07:52:52) ======

this is a most likely a missing update for the forbidden list - each step of an alien should update the forbidden list with the new alien position afair - especially since they can walk at the same time. it must also be ensured that the forbidden list is checked before each step - as another entity might get into the way in the meantime.
====== tlh2000 (2010-01-15 07:42:29) ======

the update (of the forbidden lisT) is done in AI_PrepBestAction

i&#039;ve changed the G_BuildForbiddenList in r28030 - that might fix the bug - set to pending, if you see this again, please reopen.

if we find a way or map where this occurs more often, we can set the game seed to something static to be able to reproduce the random behaviour of the aliens.
====== markhawrylak (2010-01-15 23:33:08) ======

could be related to defect 2929744
====== sf-robot (2010-01-30 02:20:12) ======

This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).