diff --git a/map65/libm65/q65b.f90 b/map65/libm65/q65b.f90
index 682b2f5a5..62e76835c 100644
--- a/map65/libm65/q65b.f90
+++ b/map65/libm65/q65b.f90
@@ -29,11 +29,13 @@ subroutine q65b(nutc,nqd,nxant,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,xpol, &
   character*12 mycall,hiscall
   character*6 mygrid,hisgrid
   character*4 grid4
+  character*28 msg00
   character*80 line
   character*80 wsjtx_dir
   character*1 cp,cmode*2
   common/cacb/ca,cb
   common/early/nhsym1,nhsym2,ldecoded(32768)
+  data nutc00/-1/,msg00/'                            '/
   save
 
   open(9,file='wsjtx_dir.txt',status='old')
@@ -172,9 +174,14 @@ subroutine q65b(nutc,nqd,nxant,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,xpol, &
           ':',cp,cmode
 1014 format(f8.3,i5,3i3,f5.1,i4,i3,i4,i5.4,4x,a22,1x,2a1,2x,a2)
 
+! Suppress writing duplicates (same time, same decoded message) to map65_rx.log
+     if(nutc.ne.nutc00 .or. msg0(1:28).ne.msg00) then
 ! Write to file map65_rx.log:
-     write(21,1110)  freq1,ndf,xdt0,npol,nsnr0,nutc,msg0(1:28),cq0
-1110 format(f8.3,i5,f5.1,2i4,i5.4,2x,a28,': A',2x,a3)
+        write(21,1110)  freq1,ndf,xdt0,npol,nsnr0,nutc,msg0(1:28),cq0
+1110    format(f8.3,i5,f5.1,2i4,i5.4,2x,a28,': A',2x,a3)
+        nutc00=nutc
+        msg00=msg0(1:28)
+     endif
   endif
 
 900 close(13)