Just a clarification coz I'm tired and a few beers into this cold windy night..
So if I sparge into the fermenter, mix to get a consistant SG, split between two pots....I can...
Only add hops to one of the boils in the same amount I would for a full boil seeing its the SG of the brew and the IBU's and aroma etc will be diluted by the other unhopped wort just like a K&K would with extra malt.
In that case couldn't I cut down on the time spent boiling wort by only boiling the top up wort for say 20 mins rather than an hour? Just basically to kill the nasties just like we do when steeping grains. Or does the full boil of AG wort have other benifits?
I assume the trouble might come into it with the evaporation rate and that two boils would evaporate more than the one pot of the combined amounts. Dr S's 90 boil loses 9L in total over the 90 mins ending up with 20Ls which is the perfect amount for my kegging needs. I wonder if I'll actually end up with less than 20LS in total using my two boils method. Its a pain in the arse but till I get my Urn I'm stuck and my stove would struggle or take days to boil 29L's
EDIT. I must be tired as Warra replied right at the top saying half the hops in half the amount but just wondering about the other way as I might cut out 40 mins of boil time on the second wort boil.