Parallel Fusing sounds dangerous,
I've come across this a number of times,
especially where the fact is not marked.
Causes a bit of confusion, if you are trying to Isolate a circuit, it's almost like a Ring Circuit, but it's not!.
Pull one fuse, the voltage drops to 220 odd volts, pull another, nothing changes, try and find the other leg of the circuit.
This sort of wiring, should be outlawed! [Linked Image]
Especially where Poly-Phase circuits are concerned.