Assumption. Two shields only granted DV bonus from better one suggesting that option was thought out.
You get PV from both, full DV from both, and full DV from the skill bonus of the higher. Overall much better than spear + shield in terms of defence, especially since it's easier to train shield marks like this (with a spear you have to train it up to get the DV, which is a chore). The only reason to wear a spear is if you want to melee things now and then, in which case you're better off with a better weapon than most crappy spears.
I've often argued that many players are way too fixated on the spear + shield combo. People often stick to it above clearly superior combos. I've seen flgs with a crappy spear equipped whilst an adamantium longsword of destruction sat in the backpack, all because of this stupid spear obsession.
I've been making suggestions for staffs to be improved somehow for wizards to make them more attractive above spear + shield. Some change akin to this may happen in future. The nice thing in general is that things are changing and voices for balance are being listened to.
I like many changes too. Especially breaking RoDS wish engine. Still, I can't help but think some things Thomas does are not for the best. Back when ADOM was running its campaign I was unemployed and missed out on backer benefits. Today I am glad that no money was spent.
Heh, that's the problem with crowdfunding campaigns - everyone assumes they'll get exactly what they want out of it. But hell, any responsiveness to change is good. If you want something changed, suggest it!
Also, some of the cool additions totally outweigh any slightly negative changes. I'd take chaos knights and duelists over dual-shielding any day.