diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
index fa9125b782f85..54be4f112ef55 100644
--- a/net/bluetooth/hci_request.c
+++ b/net/bluetooth/hci_request.c
@@ -932,7 +932,7 @@ static bool scan_use_rpa(struct hci_dev *hdev)
 
 static void hci_req_start_scan(struct hci_request *req, u8 type, u16 interval,
 			       u16 window, u8 own_addr_type, u8 filter_policy,
-			       bool addr_resolv)
+			       bool filter_dup, bool addr_resolv)
 {
 	struct hci_dev *hdev = req->hdev;
 
@@ -997,7 +997,7 @@ static void hci_req_start_scan(struct hci_request *req, u8 type, u16 interval,
 
 		memset(&ext_enable_cp, 0, sizeof(ext_enable_cp));
 		ext_enable_cp.enable = LE_SCAN_ENABLE;
-		ext_enable_cp.filter_dup = LE_SCAN_FILTER_DUP_ENABLE;
+		ext_enable_cp.filter_dup = filter_dup;
 
 		hci_req_add(req, HCI_OP_LE_SET_EXT_SCAN_ENABLE,
 			    sizeof(ext_enable_cp), &ext_enable_cp);
@@ -1016,7 +1016,7 @@ static void hci_req_start_scan(struct hci_request *req, u8 type, u16 interval,
 
 		memset(&enable_cp, 0, sizeof(enable_cp));
 		enable_cp.enable = LE_SCAN_ENABLE;
-		enable_cp.filter_dup = LE_SCAN_FILTER_DUP_ENABLE;
+		enable_cp.filter_dup = filter_dup;
 		hci_req_add(req, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(enable_cp),
 			    &enable_cp);
 	}
@@ -1053,6 +1053,8 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
 	u8 own_addr_type;
 	u8 filter_policy;
 	u16 window, interval;
+	/* Default is to enable duplicates filter */
+	u8 filter_dup = LE_SCAN_FILTER_DUP_ENABLE;
 	/* Background scanning should run with address resolution */
 	bool addr_resolv = true;
 
@@ -1106,6 +1108,19 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
 	} else if (hci_is_adv_monitoring(hdev)) {
 		window = hdev->le_scan_window_adv_monitor;
 		interval = hdev->le_scan_int_adv_monitor;
+
+		/* Disable duplicates filter when scanning for advertisement
+		 * monitor for the following reasons.
+		 *
+		 * For HW pattern filtering (ex. MSFT), some controllers ignore
+		 * RSSI_Sampling_Period when the duplicates filter is enabled.
+		 *
+		 * For SW pattern filtering, when we're not doing interleaved
+		 * scanning, it is necessary to disable duplicates filter,
+		 * otherwise hosts can only receive one advertisement and it's
+		 * impossible to know if a peer is still in range.
+		 */
+		filter_dup = LE_SCAN_FILTER_DUP_DISABLE;
 	} else {
 		window = hdev->le_scan_window;
 		interval = hdev->le_scan_interval;
@@ -1113,7 +1128,8 @@ void hci_req_add_le_passive_scan(struct hci_request *req)
 
 	bt_dev_dbg(hdev, "LE passive scan with whitelist = %d", filter_policy);
 	hci_req_start_scan(req, LE_SCAN_PASSIVE, interval, window,
-			   own_addr_type, filter_policy, addr_resolv);
+			   own_addr_type, filter_policy, filter_dup,
+			   addr_resolv);
 }
 
 static bool adv_instance_is_scannable(struct hci_dev *hdev, u8 instance)
@@ -3135,6 +3151,8 @@ static int active_scan(struct hci_request *req, unsigned long opt)
 	u8 own_addr_type;
 	/* White list is not used for discovery */
 	u8 filter_policy = 0x00;
+	/* Default is to enable duplicates filter */
+	u8 filter_dup = LE_SCAN_FILTER_DUP_ENABLE;
 	/* Discovery doesn't require controller address resolution */
 	bool addr_resolv = false;
 	int err;
@@ -3159,9 +3177,23 @@ static int active_scan(struct hci_request *req, unsigned long opt)
 	if (err < 0)
 		own_addr_type = ADDR_LE_DEV_PUBLIC;
 
+	if (hci_is_adv_monitoring(hdev)) {
+		/* Duplicate filter should be disabled when some advertisement
+		 * monitor is activated, otherwise AdvMon can only receive one
+		 * advertisement for one peer(*) during active scanning, and
+		 * might report loss to these peers.
+		 *
+		 * Note that different controllers have different meanings of
+		 * |duplicate|. Some of them consider packets with the same
+		 * address as duplicate, and others consider packets with the
+		 * same address and the same RSSI as duplicate.
+		 */
+		filter_dup = LE_SCAN_FILTER_DUP_DISABLE;
+	}
+
 	hci_req_start_scan(req, LE_SCAN_ACTIVE, interval,
 			   hdev->le_scan_window_discovery, own_addr_type,
-			   filter_policy, addr_resolv);
+			   filter_policy, filter_dup, addr_resolv);
 	return 0;
 }
 
