And Now....... the Real Answer

:
the MPC4000 has "three" 2-pole resonant filters PER VOICE,
but they're always configured as a single filter unit,
so in that sense, it only has ONE filter PER VOICE.
(Polyphony - the number of voices - is 64..... so technically,
that's 3 x 64 software filters inside...... just image what
that would be like done in analogue electronics

)
The key is the way they are "configured" together -
what you see in the user interface is just a choice of about 30-odd different filter "types"
eg "6 pole lo-pass" (which means that you really have 3 x 2-pole lo pass in series tuned to the same thing),
or "triple", where you have the three of them side-by-side in parallel
You can read about all this in the user manual, downloadable on Akai's site...