Advanced functions (script cmdlets) use the attribute ValueFromPipeline in
order to tell which parameter is used for the pipeline input. Normally there
is one such parameter per a parameter set, or none.
It turns out PowerShell allows using several parameters with ValueFromPipeline.
Is it a feature or design flaw? Who knows, usefulness of this feature is not
clear. But if two input parameters are specified by mistake (e.g. copy/paste)
then PowerShell does not fail as one may expect, it binds them to the same
values coming from the pipeline.
Test-1.ps1 shows how a function with two ValueFromPipeline
parameters works with various inputs.