Maybe it is my perception is wrong, but I do not remember to redeem the codes. When I tried to redeem the first bundle I got an error, and when I looked all my games where there. After this I do not remember redeeming any codes, but the games are in my list, and they never asked me about my account.
On the other hand it may just be false memory comparing it with Steam where every game needed to be redeemed individually.
Well you might well be right about the 'auto-redeem', I'll have to check next time I buy a bundle from them.
They definitely don't give individual desura keys though even though it looks like they do (there's a key box for every game on desura, but when you click them all the codes are the same).