TrackChecker output for Velo tracks is not stable (failing pipeline)

https://gitlab.cern.ch/lhcb/Allen/-/jobs/12322517
Checking SciFiv6_upgrade_DC19_01_Bs2PhiPhiMD_geforcertx2080ti.txt
--- /builds/lhcb/Allen/test/reference/SciFiv6_upgrade_DC19_01_Bs2PhiPhiMD_geforcertx2080ti.txt	2021-02-24 17:46:10.000000000 +0100
+++ efficiency_SciFiv6_upgrade_DC19_01_Bs2PhiPhiMD_geforcertx2080ti.txt	2021-02-24 17:46:23.000000000 +0100
@@ -1,6 +1,6 @@
 
 Velo tracks:
-TrackChecker output                               :      1728/   222601   0.78% ghosts
+TrackChecker output                               :      1728/   222600   0.78% ghosts
 01_velo                                           :     94316/    95852  98.40% ( 98.47%),      1824 (  1.90%) clones, pur  99.72%, hit eff  96.90%
 02_long                                           :     56498/    56923  99.25% ( 99.29%),       731 (  1.28%) clones, pur  99.83%, hit eff  98.01%
 03_long_P>5GeV                                    :     39422/    39606  99.54% ( 99.56%),       393 (  0.99%) clones, pur  99.83%, hit eff  98.52%
Checking SciFiv6_upgrade_DC19_01_Bs2PhiPhiMD_x862630v4.txt
$ cat *_diff > alldiffs
$ if [ -s alldiffs ]; then echo "Differences were found against reference files."; exit 1; else echo "No differences found against reference files."; exit 0; fi
Differences were found against reference files.
Uploading artifacts for failed job
00:01
Uploading artifacts...
validation_output/*_diff: found 2 matching files and directories 
Uploading artifacts as "archive" to coordinator... ok  id=12322517 responseStatus=201 Created token=qqS5mgWN
Cleaning up file based variables
00:01
ERROR: Job failed: exit code 1