Ghost Decodes with WSJT-X 1.8

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gm1oxb
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Ghost Decodes with WSJT-X 1.8

I have recently started using WSJT-X 1.8 for receiving WSPR signals
and I have noticed a new (to me, at least) type of incorrect decode.

A correct decode is associated with a spurious "ghost" decode
at the same frequency (or 0.1Hz lower) and with a slightly lower S/N
(-3 to -6dB).

For example :

180116 1848 3 -22 -1.09 1.8381913 ZZ8XLG/6 33 0 8433 0
180116 1848 5 -17 -1.09 1.8381913 DK1BN/P 40 0 1 0

180124 0252 3 -18 2.80 0.4756993 4QC/O94SNC 7 0 8966 -64
180124 0252 5 -15 2.75 0.4756994 <G3KEV> IO94SH 37 0 1 0

180124 0552 2 -23 2.80 0.4756994 2H6/M74MYD 33 0 9363 16
180124 0552 4 -19 2.84 0.4756995 <G3KEV> IO94SH 37 0 1 0

Using WSJT-X v1.8.0 rR8193, Set to "Deep" Decode on a Windows 7/64bit computer

Has anyone else seen this type of incorrect decode?

Could these spurious decodes be created by digital signal processing in the receiver
or are they due to the "Deep" decoding in WSJT-X with unfortunate alignment of FFT bins?

I have saved the WAV files for testing on future versions of WSJT-X.

David Owen
GM1OXB