[Kenwood] Inrad #94 filter trouble

[WW3S]

I have a Inrad #94 2.1 kc SSb filter installed in my TS850. Also have a
INrad 103 400 hz cw filter. Using the stock kenwood 2.7 filter or the 400
hz, cw reception is just fine. Using the 2.1 kc filter however, I can copy
the cw note on either side of zero beat. I bought the filter used and am not
aware of any "polarity" but it appears as if someone worked on the board;
maybe soldered a new/different filter on or reversed it. Am I correct, there
is no polarity involved? Is it normal to copy on both sides with that filter
in? If so, why doesn't it work that way with the stock 2.7?

73 Jamie WW3S