replay-dual.sh/test_31 fails frequently. error messages is like below:

replay-dual test_31: @@@@@@ FAIL: 1 multiops failed
Trace dump:
= /usr/lib64/lustre/tests/test-framework.sh:6383:error()
= /usr/lib64/lustre/tests/replay-dual.sh:1262:test_31()
= /usr/lib64/lustre/tests/test-framework.sh:6704:run_one()
= /usr/lib64/lustre/tests/test-framework.sh:6754:run_one_logged()
= /usr/lib64/lustre/tests/test-framework.sh:6593:run_test()
= /usr/lib64/lustre/tests/replay-dual.sh:1264:main()