Year tag modified from FLAC to AAC FDK

[Botrax]

When converting a FLAC that contains a funky Year tag, it gets modified in FDK AAC HEv2
DBPoweramp 15.1 32-bit

-Create a FLAC
-File/Properties/ID Tag, edit YEAR, enter "2014; 2014"
-Open FLAC with Winamp. Year displays "2014"
-Convert to AAC using FDK 2.1 codec HEv2, full quality
-Open M4A file in Winamp. Year displays "20142014"

Year tag should only contain a year, but some source files have full dates or other funky date in those year fields for some reason.
FDK seems to modify them slightly somehow.