if you want to coppy objects in microsoft active directory you are able to chose wich attributes are copied. this is only a setting in th ad schema. but please be sure that you have a backup of your domain and be sure that you know what you are doing in the schema.

first you have to login on the dc that is the schema master with an account that have schema admin permissions.. open the schema manager.. go to start > run > mmc >> file > add/remove snap-in > active directory schema

if there is no option to add the schema snap-in, you have to register the dll with following command start > run > regsvr32 schmmgmt.dll

in w2k8 you have to start the mmc with right click on mmc and run as administrator

ok, now you have an mmc with the active directory schema manager open. go to attributes and search the particular attribute in the right pane > rightclick properties and uncheck the chekbox for “attribute is copied when duplicating a user”

now you are done and next time you copy a active directory object, this attribute isn’t copied