Just an FYI. Despite popular belief that breeding while giving both parents a different Power Item will result in both IVs being passed down to the egg.. it is incorrect. I've bred several eggs using this technique and doing so results in it picking one of the two IVs at random. It is possible to get the second IV passed onto the egg, but the chances of that happening are just as good as it being passed on without another power item.

I have not tested this with the Everstone yet to see if Nature and the IV can be passed on at the same time.

Well actually this is just when you factor in the Power items for HP & DEF since the IVs are passed like this...

1st = ANY
2nd = can't be HP
3rd = can't be HP or DEF

It sucks I know but hey...anyway so when giving 2 pokemon a Power Item just make sure you understand that the IVs that are garenteed to pass on will not always happen for HP & on rare occasions DEF (I guess...) due to the order in which the game passes on the IVs...enough said...I have personally got them both passed on to my pokemon when I breed inherited SPATK & DEF on multiple eggs in a row so it does...it's just that you can't control the order in which they are passed on so...back to Eevee breeding for me...

Then you must be considerably lucky, because in my particular case I used Speed and Attack. Neither which being the Defense and HP stats that you mentioned. Even if that was the case and you used a HP and Defense Power Item, your logic wouldn't hold.

I too have had both stats passed on to both eggs, however you might want to look at the parents in question, maybe they both had one of the stats you were trying to breed, thus increasing the odds that you would have the max stat passed on.

Either way, if it was a hard fast rule that the Power Items on 2 parents guaranteed that BOTH stats would be passed on, then you would NEVER have an egg that had a different stat passed on from that of a power item. My multiple test runs of having a Power Bracer on one of my pokemon with a 31 Attack and then getting an egg with a 3 in Attack or a 10.. or whatever proves that you can't be guaranteed a 2nd Power Item will work.

Well yeah, they both had 31 DEF IVs & the Ditto had 31 SPATK IVs...so maybe so...well then with that I say that this isn't exactly an Error but more of a Misinterpretation...though while both IVs weren't always passed on, they both passed on most of the time & I only hatched 3 Eggs with each Eevee I breeded with Ditto & they only pass on 3 IVs...but your point was made nonetheless...

I agree that "Error" isn't the best word since it could imply that it was a game glitch, but it fits in more with what Psypokes (and other pokemon sites) is reporting about the Power Items and Breeding: http://www.psypokes.com/hgss/breeding.php

I too saw the possibility and instantly thought that doubling up on it would work, however I think most sites went quick to post the possibility as if it was fact without testing it out.