Does this imply (1) all eggs are old or (2) some eggs are fresh?

I think (1)
Edit: I think both actually. If I had to pick I'd pick (1)

It can mean either and which would likely be understood in the context of a conversation.

We have other ways to make the meaning very clear and writers would perhaps more likely use one of these.

To make meaning (1) clear ....

[#56532] None of these eggs are fresh. (CK)

To make meaning (2) clear ...

[#56531] Not all of these eggs are fresh. (CK)

I see. φ(..)メモメモ

There is another audio here for this one.

https://audio.tatoeba.org/sentences/eng/55049.mp3

At at least, it's an alternative audio file, until this gets replaced with a non-contracted "are not" version at that location. (I do not plan to add such an audio file myself, though, since I'm more focused on producing audio for the more natural way the language is spoken.)

>It now has audio, if you're interested.
@CK, thank you! This sentence has a lot of Linking. (However, I'm not sure... It's called "Linking", right?)
>https://audio.tatoeba.org/sentences/eng/55049.mp3
Does it say "are not"? hmm.

>https://audio.tatoeba.org/sentences/eng/55049.mp3
Does it say "are not"? hmm.

It says "aren't." That's why I've unlinked it from that sentence.

@CK, thanks for the explanation. I get it! 😀