Apidya 2 doesn't exist.
I think the confusion has come from the Apidya titlescreen. If you look, it says:
Apidya: xxx II
where xxx are some Japanese characters.
Now, I don't know what the Japanese characters mean, but this suggests to me that Apidya is a 'sequel' to something (probably some obscure Kaiko game), so it is xxx 2.
However, someone who doesn't know much has probably seen this and thought that it read merely 'Apidya 2' and named an ADF 'Apidya 2' erroneously. Then, a rumour got spread round that there was a real Apidya 2.
This is my explanation - I've never heard of a sequel to Apidya, but I could be wrong. Is it possible that an AGA sequel was in the works, but wasn't released?
<Ian>
Removed Cody's double barrel screenshot.
It will be included in the upcoming AGD
</Ian>