The 6 way ADSL faceplate is made my Pressac who supply BT, it comes with BT Openreach branded instructions, the only difference between the 6 way and 3 way version is the addition of two terminals marked A & B. These are for wiring an ADSL extension off the faceplate(using the NTE2000 extension kit for example-http://www.run-it-direct.co.uk/BTNTE2000EX10M.html
As you will see below the PCB's on the rear of the filter are completely different and certainly NOT modified!
First off the 3 way version :-
An excellent quality ADSL filter, now the PCB that the customer side wiring connects to :-
Now the 6 way version :-
The same ADSL filter PCB assembly but notice how the customer side PCB is different :-

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