Translations have to pay attention to grammar, but they also have to pay attention to basic logic and cultural cues. Saying "the Logos was with God, and the Logos was God" makes no sense. It fails a basic logic test - something cannot be with something and also be that something on a normal understanding of these sorts of words. So something's gotta give. The question is what.
Moffatt's translation has the advantage of making sense. Something can be both with God and divine. The question "is it representative of the original" is vague. The question I have is, what was the intent with the original sentence? What was John trying to say? How would it typically be received? Was he trying to make a logically (seemingly) paradoxical sentence? Some trinitarians would say he was! Or was he trying to express something else?
Related to this are background beliefs about John's conception of the logos, John's conception of God, and John's conception of Jesus. It is basically impossible to translate this sentence without working beliefs about those respective concepts re John, IMHO.
If you think that logos here = Jesus = person of trinity, you might not have a problem with the typical translation, because 'God' is basically a category containing 3 persons - so the sentence makes sense (in a mysterian kind of way). It could be paraphrased as "God the Son was with God the Father, and God the Son was of the category 'God'".
Yet, is this how ancient Greek culture would have understood the term 'logos'? No. It was, indeed, something related to words - discourse, reason, God's unfolding principle - things like that. If that's your view, how do you translate the last part of John 1:1?
Consider REV commentary on John 1:1
"“the word.” “Word” is translated from the Greek word logos (#3056
λόγος ). It refers to God’s reason as played out in His plan and
purpose. It is important that Christians have a basic understanding of
logos, which is translated as “Word” in most versions of John 1:1.
Most Trinitarians believe that logos refers directly to Jesus Christ,
so in most Bibles logos is capitalized as “Word” (some versions even
put “Jesus Christ” instead of “Word” in John 1:1). However, a study of
the Greek word logos shows that it occurs more than 300 times in the
New Testament, and in both the NIV and the KJV it is capitalized only
7 times (and even those versions disagree on exactly when to
capitalize it). When a word that occurs more than 300 times is
capitalized fewer than 10 times, it is obvious that when to capitalize
and when not to capitalize is a translators’ decision based on their
particular understanding of Scripture. Below are five points to
consider. [...]"
I recommend the rest of the commentary at the link above.
As with many things in scripture, where you stand on a 'representative' translation of this line is going to depend on where you sit in terms of background beliefs about the word 'logos', the writer John's beliefs about that word, and so on. Because the REV translators understand 'logos' here as meaning roughly 'plan', they translate John 1:1 as
In the beginning was the word, and the word was with God, and what God
was the word was. (ibid.)
And what if we paraphrased it to more accurately convey the intended meaning?
Once we understand the logos in John 1:1 to be God’s purpose and plan,
we can see that if John 1:1 was written in today’s English, we would
likely say something like, “In the beginning was the plan, and God had
that plan, and what God was the plan was.”