diff --git a/src/libs/zbxconf/cfg.c b/src/libs/zbxconf/cfg.c
index 29b661deda9..456c0587abf 100644
--- a/src/libs/zbxconf/cfg.c
+++ b/src/libs/zbxconf/cfg.c
@@ -426,9 +426,9 @@ static int	__parse_cfg_file(const char *cfg_file, struct cfg_line *cfg, int leve
 
 	FILE		*file;
 	int		i, lineno, param_valid;
-	char		line[MAX_STRING_LEN + 3], *parameter, *value;
+	char		line[MAX_STRING_LEN + 3], *parameter, *value, *cfg_options_read;
 	zbx_uint64_t	var;
-	size_t		len;
+	size_t		len, cfg_size = 0;
 #ifdef _WINDOWS
 	wchar_t		*wcfg_file;
 #endif
@@ -438,6 +438,11 @@ static int	__parse_cfg_file(const char *cfg_file, struct cfg_line *cfg, int leve
 		return FAIL;
 	}
 
+	for (i = 0; NULL != cfg[i].parameter; i++)
+		cfg_size++;
+
+	cfg_options_read = calloc(cfg_size, sizeof(*cfg_options_read));
+
 	if (NULL != cfg_file)
 	{
 #ifdef _WINDOWS
@@ -497,6 +502,18 @@ static int	__parse_cfg_file(const char *cfg_file, struct cfg_line *cfg, int leve
 				if (0 != strcmp(cfg[i].parameter, parameter))
 					continue;
 
+				if (TYPE_MULTISTRING != cfg[i].type && TYPE_CUSTOM != cfg[i].type)
+				{
+					if (0 != cfg_options_read[i])
+					{
+						zabbix_log(LOG_LEVEL_WARNING, "parameter %s is listed more than once at"
+								" line %d, previous values will be ignored",
+								parameter, lineno);
+					}
+
+					cfg_options_read[i] = 1;
+				}
+
 				param_valid = 1;
 
 				zabbix_log(LOG_LEVEL_DEBUG, "accepted configuration parameter: '%s' = '%s'",
@@ -582,6 +599,8 @@ static int	__parse_cfg_file(const char *cfg_file, struct cfg_line *cfg, int leve
 		}
 	}
 
+	zbx_free(cfg_options_read);
+
 	return SUCCEED;
 cannot_open:
 	if (ZBX_CFG_FILE_REQUIRED != optional)
@@ -612,6 +631,8 @@ unknown_parameter:
 missing_mandatory:
 	zbx_error("missing mandatory parameter \"%s\" in config file \"%s\"", cfg[i].parameter, cfg_file);
 error:
+	zbx_free(cfg_options_read);
+
 	if (0 == noexit)
 		exit(EXIT_FAILURE);
 
diff --git a/src/libs/zbxpreproc/pp_error.c b/src/libs/zbxpreproc/pp_error.c
index ec432528ff7..23e9102ec25 100644
--- a/src/libs/zbxpreproc/pp_error.c
+++ b/src/libs/zbxpreproc/pp_error.c
@@ -50,6 +50,7 @@ ZBX_PTR_VECTOR_IMPL(pp_result_ptr, zbx_pp_result_t *)
  ******************************************************************************/
 void	pp_result_set(zbx_pp_result_t *result, const zbx_variant_t *value, int action, zbx_variant_t *value_raw)
 {
+	zabbix_log(LOG_LEVEL_CRIT, "DIMBUG In %s(): value:%s raw:%s", __func__, value->data.str, value_raw->data.str);
 	zbx_variant_copy(&result->value, value);
 	result->value_raw = *value_raw;
 	zbx_variant_set_none(value_raw);
@@ -303,6 +304,8 @@ void	pp_format_error(const zbx_variant_t *value, zbx_pp_result_t *results, int r
  ******************************************************************************/
 int	pp_error_on_fail(zbx_variant_t *value, const zbx_pp_step_t *step)
 {
+	zabbix_log(LOG_LEVEL_CRIT, "DIMBUG In %s()", __func__);
+
 	switch (step->error_handler)
 	{
 		case ZBX_PREPROC_FAIL_DISCARD_VALUE:
@@ -318,5 +321,7 @@ int	pp_error_on_fail(zbx_variant_t *value, const zbx_pp_step_t *step)
 			break;
 	}
 
+	zabbix_log(LOG_LEVEL_CRIT, "DIMBUG End of %s():%d", __func__, step->error_handler);
+
 	return step->error_handler;
 }
diff --git a/src/libs/zbxpreproc/pp_execute.c b/src/libs/zbxpreproc/pp_execute.c
index fdc6d211fcc..5ed42419ad0 100644
--- a/src/libs/zbxpreproc/pp_execute.c
+++ b/src/libs/zbxpreproc/pp_execute.c
@@ -1242,6 +1242,8 @@ void	pp_execute(zbx_pp_context_t *ctx, zbx_pp_item_preproc_t *preproc, zbx_pp_ca
 		if (SUCCEED != pp_execute_step(ctx, cache, um_handle, preproc->hostid, preproc->value_type, value_out,
 				ts, preproc->steps + i, &history_value, &history_ts, config_source_ip))
 		{
+			zabbix_log(LOG_LEVEL_CRIT, "DIMBUG %s(): pp_execute_step() failed", __func__);
+
 			zbx_variant_copy(&value_raw, value_out);
 			if (ZBX_PREPROC_FAIL_DEFAULT == (action = pp_error_on_fail(value_out, preproc->steps + i)))
 				zbx_variant_clear(&value_raw);
@@ -1270,6 +1272,8 @@ void	pp_execute(zbx_pp_context_t *ctx, zbx_pp_item_preproc_t *preproc, zbx_pp_ca
 
 	if (ZBX_VARIANT_ERR == value_out->type)
 	{
+		zabbix_log(LOG_LEVEL_CRIT, "DIMBUG %s(): value_out->type:ZBX_VARIANT_ERR", __func__);
+
 		/* reset preprocessing history in the case of error */
 		if (NULL != history)
 		{