Your are right of course. I just assumed it's UB, since it's the only mod that changed this file...
I turned out, that the real culprit is Dudley Fix pack (
http://forgottenwars.com/dudleyfix/bg1_scripts.htm)
FTOBE5.DLG, DIALOG.TLK string 1250* Dialog Error
Commoner, AR3327 - when charmed the commoner fails to give the ring she says she is giving you. No specific ring is mentioned in the original dialogue so I suggest a Gold Ring which would seem in keeping with her spellbound love. The dialogue fix should only allow her to offer the gift once.
Add trigger in [State 3] StateCheck(Myself,STATE_NORMAL).
Add trigger in [State 4] Global("DXFtobe5","GLOBAL",0).
Add actions in [State 4] GiveItemCreate("RING10",LastTalkedToBy()) and SetGlobal("DXFtobe5","GLOBAL",1).
Add trigger in [State 6] StateCheck(Myself,STATE_NORMAL).
Edit [State trigger 5] to read StateCheck(Myself,STATE_CHARMED) Global("DXFtobe5","GLOBAL",1).
Create new string 1250 "Is there anything else I can do to please you?"
Change Response in [State 5] to StringRef 1250.
Re-order State triggers as follows: Charmed (Global 0) then (Global 1), NumTimesTalked To (0) as original sequence, Normal (Num1) then (Num2); this is order 4, 5, 0, 1, 2, 3, 6.
Some fixes overlap, and in this case, the fixpack introduced this bug. This also explains why I get 2 rings from her as well as from another charmed Noble (one ring added by the fixpack, another by UB).
Can anyone tell me then whether the fixpack is needed at all? Are all the fixed already introduced in UB? I can't find any contact information on the forgottenwars webiste, other than a link to PocketPlane...