On a side note ... there are few experiences in life that compare to listening to "Aegean Sea" on headphones, stoned out of one's gourd, whilst looking over the deck of a ferry crossing the Aegean Sea. I'd unreservedly recommend this to anyone who hasn't tried it.
I don't know which double CD version you're referencing. Is it this one?
https://www.discogs.com/Aphrodites-Child-666/release/10918712
This is the double CD I had back in the mid-1990s. It matched the original LP mix exactly.
Nowadays, the original LP mix of "666" can fit on a single CD -- even with a total time of approximately 78:00.
The Greek LP mix total time: 82:05.
The Japanese SHM-CD total time: 78:50 (on one CD, no less.)
This includes something weird: a spoken "Do it!" (from the same-named song) is thrown on the end right after the final song, "Break." I've never heard this on any LP pressing: US, UK, or Greece. (If you have, let me know, OK?)
Yes, it looks identical to the disc in the link, but it also has the spoken "Do It!" after "Break". I only bought it about twelve years back so maybe it's a later pressing that was cloned form the Japanese disc? The mystery thickens.
The timings are indeed the same as the album timings listed on Discogs though - turned out the misinformation about it being longer was from an Amazon reviewer who'd got their facts wrong.