How to populate another column with a sequence value generated for an identity column?
If you have a condition that specifies 1005 whether root_id has to get the same value as unique_id, you could use a TRIGGER. Something like this:

CREATE OR REPLACE TRIGGER root_unique_trg
    BEFORE INSERT
    ON UNIQUE_PHYSICIAN
    FOR EACH ROW
    WHEN (NEW.is_root_phys = 1)
BEGIN
    :NEW.root_id := :NEW.unique_id ;
END ;


Tested in SQLfiddle