There is a problem with a cheap fuse in series with the proper HRC fuse. With a DC source it is possible and not that unlikely that the cheap fuse can blow but not quench the arc, even with a current not large enough blow the higher rated HRC one. The extra heat will become a problem where the HRC fuse will not help with very much. The smaller fuse may still be OK, but should still be DC rated and thus not a really cheap one. This is kind of the price you have to pay for a CAT 3 rating.
A 440 mA fuse will likely not blow at 441 mA, but legally there is a chance it could. It usually takes more like twice the current to reliably blow the fuse, but some may bow earlier.
I see no real problem if the fuse would even well exceed the nominal range, like a 440 mA fuse in a 200 mA range, as long as the protection is up to it. Especially for the lower range a slightly larger fuse rating would be preferable and would also allow lower burden and less heat under normal conditions. However it still needs the protection (diodes) to be good for the higher current. This may need re-certification / testing and is thus not a change to be made easy.