WSPRx Duplicate decodes separated by 12 Hz running Linux, linHPSDR and WSJTx

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W0AY
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WSPRx Duplicate decodes separated by 12 Hz running Linux, linHPSDR and WSJTx

Setup: Linux Ubuntu 18.04 running linHPSDR which controls my Apache Labs 100D SDR, which feeds a pulseaudio nullsink. The monitor of the nullsink is fed to WSJTx. On strong signals (usually >0 db as reported by WSJTx) I frequently see multiple decodes whose frequencies are separated by 12 Hz (sometimes 11 sometimes 13). Note this is not the usual 60Hz AC introduced side bands. Tried all manner of levels, duplicated the problem on a different PC and different radio. When the radio headphone jack is connected with a stereo cable to the mike input which in turn feeds WSJTx, the multiple decodes never occur even on "strong clear" signals. Common to all setups when the duplicate decodes show up is pulseaudio's null sink module. This can be viewed as a virtual audio cable. And yes, it is clocked at 48000. Would like to solve this because with my Apache Labs 100D, one instance linHPSDR (which can spawn up to 7 receivers) and multiple copies of wsjtx (wjstx --rig-name=rx# &), I can cover at least four WSPR bands. Any one else experience this problem?