IMO, that means that a 2x20 A8 should have almost same performance, turning, etc than a 4x20 A5.
Well two things are different, the engine and the weight.
The Fw 190A-8 in the manual (and presumably in AH) uses a boost control override system that gives it something like 300 more HP than the A-5 engine when using WEP.
The normal loaded weight of the AH A-8 is 9682 lb which conforms with the normal loaded weight in the manual. But the AH A-5 weighs 8583 lb. Even if you account for the difference in armament, this A-8 would still be heavier.
BTW the 8583 lb weight precisely matches the weight of the USAAF's Fw 190G-3 which had all armament, ammunition, and bomb racks removed. A-5 and G-3 shared airframe, engine, avionics, etc, so I think the A-5 in the game is something like 500-700 lb underweight. I did some more precise calculations on this forum a long time ago, maybe I can find them with the search feature...
The A-5 performance in AH very closely matches the USAAF's performance curves for the G-3, so closely that I think the USAAF curves were the source for the plane's performance in the game. I had a copy of some pages of this report on the web but they are lost now. I will try to put them back online soon.