Hello Ankhefenamun. Just to apologise, I haven't been around recently because of exams and things, but I'm back now.
OK. 'Nfr,' I am sure you are aware, is the Hieroglyphic adjective of great (or perhaps absolute) endearment. Whilst Egyptologists are not sure of its exact meaning, it is safe to assume that it carries a meaning relating to goodness, perfection and beauty. I like to see this as an indication that the Egyptians saw beauty in goodness, not just in physical appearance. Of course one could argue the opposite.
In Egyptian adjectives can also serve as nouns, so 'nefer' may not always mean 'beautiful,' it sometimes means 'beauty.' This is a key point to make, and I'll bring it back later.
You may be correct when you say that 'nfr-nfrw' seems like tautology, or redundancy (if we consider each word to mean the same thing, which I don't - I'll explain it later). When put into the context of Egyptian however, this may not really be the case. In one of the earlier chapters of Gardiner's EG, we encounter the dual adjectival endings, '.wy' and '.ty.' These can be used not only (as one would guess) to double up an adjective to agree with a dual subject (eg. the two good sons), but also to *double* the emphasis of an adjective when the subject is singular (eg. 'twice great is this house', i.e 'this house is better than just 'aa,' it's 'aa.wy,' it's doubly great!').
This may clarify how in Egyptian tautology is perfectly acceptable, and it was brings emphasis to an adjective or phrase that is of importance. With 'nfr' and 'aa,' repetition is even more permissable, as these common words to my mind probably had more than one meaning, more than one connotation. In English you might say 'The short man went on a brief holiday," where in a more limited language you would be forced to say "the short man went on a short holiday." Clearly the two words have completely different meaning when put into context, despite the fact that they are both adjectives.
Right, now that's out of the way, let's go into the example you give 'nfr-nfrw.' On its own, this would appear to mean 'beautiful-beautiful,' but if we place it in context then its meaning to me becomes clearer. A phrase in Egyptian should always start with the verb, unless it is a sentence of *adjectival predicate* which this one is (wow! That sounds horribly impressive!). This means that something "is beautiful or perfect," in the case of "Neferneferu - aten," it is the 'itn' that is. So, we end up with:
"The Beauty of the Perfect Aten"
I normally translate 'nfr-nfrw' as "the beauty of the perfect. . ." or "the perfection of the beautiful. . . ." Whichever sounds better in context. Either are acceptable.
I hope that answers your question- I'm glad to be back!