diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 3a2abae5993e..037cb3e84330 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -9,6 +9,7 @@ readonly KSFT_SKIP=4
 readonly KSFT_TEST="${MPTCP_LIB_KSFT_TEST:-$(basename "${0}" .sh)}"
 
 MPTCP_LIB_SUBTESTS=()
+MPTCP_LIB_SUBTESTS_DUPLICATED=0
 
 # only if supported (or forced) and not disabled, see no-color.org
 if { [ -t 1 ] || [ "${SELFTESTS_MPTCP_LIB_COLOR_FORCE:-}" = "1" ]; } &&
@@ -146,12 +147,26 @@ mptcp_lib_kversion_ge() {
 	mptcp_lib_fail_if_expected_feature "kernel version ${1} lower than ${v}"
 }
 
+__mptcp_lib_result_check_duplicated() {
+	local subtest
+
+	for subtest in "${MPTCP_LIB_SUBTESTS[@]}"; do
+		if [[ "${subtest}" == *" - ${KSFT_TEST}: ${*%% #*}" ]]; then
+			MPTCP_LIB_SUBTESTS_DUPLICATED=1
+			mptcp_lib_print_err "Duplicated entry: ${*}"
+			break
+		fi
+	done
+}
+
 __mptcp_lib_result_add() {
 	local result="${1}"
 	shift
 
 	local id=$((${#MPTCP_LIB_SUBTESTS[@]} + 1))
 
+	__mptcp_lib_result_check_duplicated "${*}"
+
 	MPTCP_LIB_SUBTESTS+=("${result} ${id} - ${KSFT_TEST}: ${*}")
 }
 
@@ -206,6 +221,12 @@ mptcp_lib_result_print_all_tap() {
 	for subtest in "${MPTCP_LIB_SUBTESTS[@]}"; do
 		printf "%s\n" "${subtest}"
 	done
+
+	if [ "${MPTCP_LIB_SUBTESTS_DUPLICATED}" = 1 ] &&
+	   mptcp_lib_expect_all_features; then
+		mptcp_lib_print_err "Duplicated test entries"
+		exit ${KSFT_FAIL}
+	fi
 }
 
 # get the value of keyword $1 in the line marked by keyword $2