method clone() returns a new Cursor instance with references on parent Cursor.

simple example

c=db.list.find({})
print c.Cursor_spec
c2=c.clone()
c2.Cursor_spec['_id']=1
print c.Cursor_spec
print c2.Cursor_spec

I get output
{}

probably better to do a copy all arguments so that can change the clone without consequences.