Allowing multiple filters to be used chained together is most definitely something we want to support, although in most cases they would probably be different filters, say array to extract one value followed by a deadband filter say, possibly with a time stamp filter as well. Repeating the same kind of filter seems less necessary, but given that we can support it at no cost I don’t see why we should try to prevent it.
For the array filter, I would say that having two in a filter chain is not redundant if there is a filter in between the two that changes the meaning of data, i.e., an array-to-array function like FFT. Looking at a region of interest, Fourier-transform, then look at a specific part of the spectrum. Don't know if that is a valid use case, though, and there is no FFT filter.
Two array filters in a row seem redundant.
Cheers,
~Ralph
