I think a simgle turbo would be better.
If you have 2, each will be only getting 1/2 the volume of exhaust to spin them. You'll get low boost. Yeah i know- you only need 1/2 the boost for 1/2 the cylinders blah blah blah. But you have to factor in the loss of energy. Turbos are efficient, but 2 of them is doubling the efficientlessness (or some other smart sounding word).