significant batch differences?

I brewed two Belgian Strong Dark Ales two weeks apart.

only differences being:

primary time...first batch two weeks
the second batch was in there for just under three weeks

pitching rate...first batch had two different White Labs vials pitched.
second batch pitched on first's yeast cake

pitching temp...first batch 78°F
second batch 64°F

ambient fermentation temps for both was 68°F

OG was within .001 of each other

FG on first batch was 1.017
second batch was 1.008


FG seems like a significant difference, doesn't it??

alot more yeast...more time to ferment. makes sense that it got down further. what was the OG? was it an extract batch?

yes, extract with steeping grains (and sugars).

OG's were 1.076 & 1.075

the first batch stopped at 1.017 at the two week mark

that is decent attenuation for the first one...the second is crazy, almost 90%!!

store those suckers for 6 months and save some bottles even longer. they'll be great.

so what's likely to happen if I brew ANOTHER one on this yeast cake?

I was thinking of upping the extract & steeping grains amount for a really big beer. I tasted the hydrometer samples on these two and they seem "mellow" already. (I realize they aren't carbonated)

appreciate the replies.