If the order of the source directories is known statically, that is if
"/**" is not used in the string list Source_Dirs, then there may
be several files with the same source file name sitting in different
directories of the project. In this case, only the file in the first directory
is considered as a source of the project and the others are hidden. If
"/**" is used in the string list Source_Dirs, it is an error
to have several files with the same source file name in the same directory
"/**" subtree, since there would be an ambiguity as to which one should
be used. However, two files with the same source file name may exist in two
single directories or directory subtrees. In this case, the one in the first
directory or directory subtree is a source of the project.
If there are two sources in different directories of the same "/**"
subtree, one way to resolve the problem is to exclude the directory of the
file that should not be used as a source of the project.