Fuses in Series for High Voltage Where Maximum Current is Low
This is bad idea.

If one of fuses blows, the arc will be striked, what results in lowering the voltage drop on this fuse to circa 50...150V. Then, if current will remain sufficient to blow the second fuse, the second fuse blows, and near full voltage (minus arc voltage drop on first fuse) will strike the arc in this second fuse too. 

As the result you will have arc in both fuses.