E2161 Duplicate string

I am trying to use this function for looking up mime types:

http://www.swissdelphicenter.ch/torry/showcode.php?id=2285

The resource file it comes with has hundreds of strings in it, but I 
have stripped it down to just one:

STRINGTABLE
BEGIN
101, ".3dm x-world/x-3dmf"
END

The project will not compile with this error:

[Pascal Error] E2161 Duplicate string:  ID 101; File ...\mimetypes.res 
string kept: ".3dm x-world/x-3dmf"; file ...\mimetypes.res resource 
discarded: ".3dm x-world/x-3dmf".


Any idea whats wrong?

Thanks