The problem is that you have your STATIC_ROOT as one of the STATICFILES_DIRS. The STATIC_ROOT directory should be empty, that is where all the static files from different places will be gathered when you run collectstatic. You should probably create a static directory under the myapp directory and move all your static files there. Leave the STATIC_ROOT setting as you have it now, and don't specify STATICFILES_DIRS. By default django looks in static directories under all apps in INSTALLED_APPS.
For more information please refer this discussion: https://mail.google.com/mail/ca/?shva=1#sent/13cc5c3b876dcb8d