For labels with line breaks MapGuide/AIMS displays an additional character if the label is defined as MTEXT. The character is not displayed in Map nor does it get exported / appears in drawings created with _maptoacad.
|Line break in MText - additional character is displayed in AIMS.|
Switch from MTEXT to TEXT in your label layer (or you could replace the existing line break with MText compatible line break: "\P" using SQL). If you switch Mtext to Text (at least in Studio) you will loose some format settings - such as Font height.
Has been reported to and confirmed by Autodesk Support.
To check which character-code is used for line breaks use DUMP command in Oracle sql:
SELECT text, dump( text, 1013 ) from p1 where text like '%(enter)%';
Typ=1 Len=30 CharacterSet=WE8MSWIN1252: 108,105,110,101,49,13,10,108,105,110,101,50,13,10,108,105,
typical combination for Windows based systems: 13,10
10 - line feed
13 - carriage return
Map 2013 SP2, AIMS 2013