It should be common knowledge that AD (or Windows technology) does not differentiate cases in names (including folders and files names). This means that “HappyGoLucky” is the same as “happygolucky” in Windows.
However, UNIX names are case sensitive, even folder and files names are case sensitive. This makes sense as it does make coding easier and “a” and “A” a represented different in ASCII. Of course, a persistent issue will be psychological distance. For example, “HappyGoLucky” looks very similar to “HappyGoLuCky”, but the system will refuse to accept it as an existing name. Of course, such incidents can be avoided.
Now when these 2 systems start to talk to each other, you may situations when the UNIX system will not recognise your Windows user name (e.g. TanBeeSoon), because it needs to be “tanbeesoon” instead.
If we go into AD Users and Computers (ADUC) and attempt to rename that name to all lower case, you will be frustrated because Windows thinks that they are the same and your changes will not be made. The trick then is to rename the original name to something else, e.g TanBeeSoon1, wait for replication to complete, then rename it to the original name with all lower case, “tanbeesoon”. If you don’t wait for replication (or the GCs to be updated) to complete, you will get an error saying that the name already exists.