If the MMU receives a command LoadFilament with a slot number SL we reject
the command to avoid moving the selector (effectively cutting the piece of filament present in FINDA).
That includes the scenario when the selector is standing at the very same slot SL, because the filament could be held by the printer (i.e. loaded in the nozzle).
There is one special case though - same slot AND filament load state == InSelector (it MUST NOT be anywhere farther)
D.R.racer