This problem is similar with LU-3846 and LU-3858. The test suit should wait for a few seconds after it clear the stripe of the directory. Otherwise, the newly created entries under the directory will have 2 stripe counts rather than 1.
LU-7071 Interop 2.5.3<->master DNE: sanity test_56a failed: /usr/bin/lfs getstripe --obd wrong: found 6, expected 2
LU-3846 Sanity 56u error with two OSTs
LU-3858 sanity test_27A: @@@@@@ FAIL: stripe count -1 != 1