McCarthy's eval correction?

In trying to understand McCarthy's eval, I have one question left
unresolved.  Let me give a code snippet of eval, which is written in
Common Lisp, taken from Paul Graham's draft.

```
(defun eval. (e a)
  (cond
    ...
    ((eq (caar e) 'label)
     (eval. (cons (caddar e) (cdr e))
            (cons (list (cadar e) (car e)) a)))
    ...
    ))
```

I wonder what practical difference does it make to, instead, write eval
like this:

```
(defun eval. (e a)
  (cond
    ...
    ((eq (caar e) 'label)
     (eval. (cons (caddar e) (cdr e))
            (cons (list (cadar e) (caddar e)) a)))
    ...
    ))
```

Anyone?

In my opinion, it makes no practical difference, and this correction
avoids unnecessary double processing.

--
The pioneers of a warless world are the youth that
refuse military service. ~ Albert Einstein