In short, Moore is not content to repeat the contradiction noted above, which consists in holding together the assertion that nothing can be substituted for "good", and then giving a synonym for it at the same time. He aggravates this contradiction by giving several synonyms. Moreover, what completes this error is the fact that the synonyms he gives each have a completely unique meaning, and that none of them can be reduced analytically to any other without serious alteration of meaning (even if we can conceive of the possibility of a synthetic link). It is a bit like saying: "giraffe" has four synonyms: "cat", "leg", "chair" and "interest".

In Chapter 1, Moore once again implicitly equates the concept of good and duty when responding to an objection. The objection, raised by the hedonist, is that perhaps the good is an "empty shell":
[This is the hedonist speaking]: [...] Most people have used the word [good] for what is pleasant and for what is desired respectively.
[Moore's response:] [...] Nor do I think that [he] would be willing to allow that this was all he meant. They are all so anxious to persuade us that what they call the good is what we really ought to do. Do, pray, act so, because the word good is generally used to denote actions of this nature: such, on this view, would be the substance of their teaching. And in so far as they tell us how we ought to act, their teaching is truly ethical, as they mean it to be ¹.

In other words, the debate between the hedonist and Moore is not simply verbal. They are not giving a different content to the same word (good) that would in itself have none. They both agree that the content of the word good is "what one ought to do" (duty), and they differ on whether the concept of duty can be reduced to that of pleasure or is independent of it.
In any case, Moore is asserting here, rather indirectly, that the word good, although defined as unanalysable because simple, contains the concept of duty.

Two other occurrences can be noted, which we shall pass over briefly.

Firstly, in Chapter 2: If [these theories were] true, they would simplify the study of Ethics very much. They all hold that there is only one kind of fact, of which the existence has any value at all. But they [all consider] that the main reason why the single kind of fact they name […] is that it has been held to define what is meant by good itself ². Moore admits here that "good in itself" is equivalent to the concept of "that whose existence has value".

Secondly, in Chapter V, he shows that to find out what our duty is, we need to find out which action in a given situation produces the most value, in itself and in its effects, and then (as if they were equivalent) produces the most good: We must have all this causal knowledge, and further we must know accurately the degree of value both of the action itself and of all these effects
[…] And not only this: we must also possess all this knowledge with regard to the effects of every possible alternative; and must then be able to see by comparison that the total value due to the existence of the action in question will be greater.
But it is obvious that our causal knowledge alone is far too incomplete for us ever to assure ourselves of this result, that an action is our duty: we can never be sure that any action will produce the greatest value possible.
Ethics, therefore, is quite unable to give us a list of duties: but there still remains a humbler task which may be possible for Practical Ethics […] there may be some possibility of shewing which among the alternatives, likely to occur to any one, will produce the greatest sum of good ³.

Here again, then, value, good and duty are confused.

1. Ibid., chap. 1, §11
2. Ibid., chap. 2, §24
3. Ibid., chap 5, §91