Here's a link that goes through several possibilities that could set a P2099 DTC... This might help. I still think simultaneous failure of both turbos without unusual noises or worse is unlikely. Even low oil pressure, EGR valve, or any one of a number of faulty sensors can do it on FMC products. So check this out:
http://www.obd-codes.com/p0299
Hope it helps.
http://www.obd-codes.com/p0299
Hope it helps.