I recently noticed that when my script wrote a file (e.g. condition_pd_vs_hc.pdf) into the Linux server disk mounted in my Mac. It will override another existing file although with different file name (e.g. CONDITION_PD_vs_HC.pdf). It turned out that my Mac OS filesystem is HFS+ and the disk was formated as "Mac OS Extended" (by default). Unlike "Mac OS Extended (Case-sensitive, Journaled)", "Mac OS Extended" is not case-sensitive, but case-presertive. "This means that the file system will consider foo and FoO to be the same, but when you create a new file it will remember which letters where capitalized and which were not." (quoted from https://apple.stackexchange.com/a/22304).
I totally don't get the point to have a case-insensitive but case-preserving file system. Bummer!