problem in creating DialogBox in PellesC v6.00.2

[blzbb]

it seem there problem in creating new Dialog,
this is my work i do:
1 - create empty win32 project
2 - add new resource to project
3 - add new dialog box to resource
4 - modify dialogbox name to IDD_MAIN
5 - now when i add another dialog box it's name automatically change to IDD_MAIN and when i try changing it to another name it alert me "The ID number 1001 is already used by another symbol" and i must increase ID manualy then changing the name.

i don't know it is a bug.