Did you mix 25 parts Rodinal to 1 part water AGAIN? So that's why you wanted the big bottles.
I have used Rodinal quite a lot (and I have way more than just 2 big bottles at home<g>). I can say that I have never seen it change activity as it gets older. I am using stuff that must be 5+ years old and it hasn't changed that I know of.
You're in a good position to verify this, though. One bottle I sent you was old and the other was bought new at the store just a few days before I shipped it. So, why don't you try a little from each bottle and let us know, eh? I know the store and they turn over inventory fast so it didn't sit there for more than a month at the most. Do you see much difference in the stock color - I'd expect the older one to be quite a bit darker than the newer one.
I would expect a noticible difference even between the 14 and 11 minute negatives. If you checkout my gallery, you'll see the boulder in the stream. That is EFKE 100 in 1:50 Rodinal for 13 minutes. I 'placed' the shadow in the boulder at a little above Zone III and the hot spots on the rock fell like on Zone X. I had not done dev. time tests (shame on me) so I just took published numbers for this combo. It seemed to work out ok - but the negative is very contrasty. It is giving AZO Gr 2 a tough time so far.
But I don't consider these densities abnormal. I know that I was using old Rodinal and if I cut the time back to even 11 minutes, the densities would certainly have dropped.
So, I can't account for what you're seeing. If it's due to the age of the developer, that would have to be one heck of a lot of more activity to account for what you're seeing.
Oh, in case you're wondering, I did NOT mix in any chemical into the Rodinal that I shipped - that's a dirty trick that even I would not do!
Take care and keep me posted. I can always send more......Hey this isn't just a ploy to get 'fresh' Rodinal out of me is it?