diff --git a/CHANGELOG.md b/CHANGELOG.md
index 088df83..596457d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ If you configure application using `.yaml` file change:
 
 ### Added
 - Support the `Date` header on upload (#214)
+- Add error response on attribute duplicates (#221)
 - Timeout for individual operations in streaming RPC (#234)
 
 ## [0.25.0] - 2022-10-31
diff --git a/integration_test.go b/integration_test.go
index 4607ef6..d7cb8d0 100644
--- a/integration_test.go
+++ b/integration_test.go
@@ -67,6 +67,7 @@ func TestIntegration(t *testing.T) {
 		require.NoError(t, err, version)
 
 		t.Run("simple put "+version, func(t *testing.T) { simplePut(ctx, t, clientPool, CID, version) })
+		t.Run("put with duplicate keys "+version, func(t *testing.T) { putWithDuplicateKeys(t, CID) })
 		t.Run("simple get "+version, func(t *testing.T) { simpleGet(ctx, t, clientPool, ownerID, CID, version) })
 		t.Run("get by attribute "+version, func(t *testing.T) { getByAttr(ctx, t, clientPool, ownerID, CID, version) })
 		t.Run("get zip "+version, func(t *testing.T) { getZip(ctx, t, clientPool, ownerID, CID, version) })
@@ -171,6 +172,43 @@ func makePutRequestAndCheck(ctx context.Context, t *testing.T, p *pool.Pool, cnr
 	}
 }
 
+func putWithDuplicateKeys(t *testing.T, CID cid.ID) {
+	url := testHost + "/upload/" + CID.String()
+
+	attr := "X-Attribute-User-Attribute"
+	content := "content of file"
+	valOne, valTwo := "first_value", "second_value"
+	fileName := "newFile.txt"
+
+	var buff bytes.Buffer
+	w := multipart.NewWriter(&buff)
+	fw, err := w.CreateFormFile("file", fileName)
+	require.NoError(t, err)
+	_, err = io.Copy(fw, bytes.NewBufferString(content))
+	require.NoError(t, err)
+	err = w.Close()
+	require.NoError(t, err)
+
+	request, err := http.NewRequest(http.MethodPost, url, &buff)
+	require.NoError(t, err)
+	request.Header.Set("Content-Type", w.FormDataContentType())
+	request.Header.Add(attr, valOne)
+	request.Header.Add(attr, valTwo)
+
+	resp, err := http.DefaultClient.Do(request)
+	require.NoError(t, err)
+
+	defer func() {
+		err := resp.Body.Close()
+		require.NoError(t, err)
+	}()
+
+	body, err := io.ReadAll(resp.Body)
+	require.NoError(t, err)
+	require.Equal(t, "key duplication error: "+attr+"\n", string(body))
+	require.Equal(t, http.StatusBadRequest, resp.StatusCode)
+}
+
 func simpleGet(ctx context.Context, t *testing.T, clientPool *pool.Pool, ownerID user.ID, CID cid.ID, version string) {
 	content := "content of file"
 	attributes := map[string]string{
diff --git a/uploader/filter.go b/uploader/filter.go
index e453cfe..c7349c7 100644
--- a/uploader/filter.go
+++ b/uploader/filter.go
@@ -26,7 +26,8 @@ func systemTranslator(key, prefix []byte) []byte {
 	return bytes.ToUpper(key)
 }
 
-func filterHeaders(l *zap.Logger, header *fasthttp.RequestHeader) map[string]string {
+func filterHeaders(l *zap.Logger, header *fasthttp.RequestHeader) (map[string]string, error) {
+	var err error
 	result := make(map[string]string)
 	prefix := []byte(utils.UserAttributeHeaderPrefix)
 
@@ -42,23 +43,30 @@ func filterHeaders(l *zap.Logger, header *fasthttp.RequestHeader) map[string]str
 		}
 
 		// removing attribute prefix
-		key = bytes.TrimPrefix(key, prefix)
+		clearKey := bytes.TrimPrefix(key, prefix)
 
 		// checks that it's a system NeoFS header
 		for _, system := range neofsAttributeHeaderPrefixes {
-			if bytes.HasPrefix(key, system) {
-				key = systemTranslator(key, system)
+			if bytes.HasPrefix(clearKey, system) {
+				clearKey = systemTranslator(clearKey, system)
 				break
 			}
 		}
 
 		// checks that the attribute key is not empty
-		if len(key) == 0 {
+		if len(clearKey) == 0 {
+			return
+		}
+
+		// check if key gets duplicated
+		// return error containing full key name (with prefix)
+		if _, ok := result[string(clearKey)]; ok {
+			err = fmt.Errorf("key duplication error: %s", string(key))
 			return
 		}
 
 		// make string representation of key / val
-		k, v := string(key), string(val)
+		k, v := string(clearKey), string(val)
 
 		result[k] = v
 
@@ -67,7 +75,7 @@ func filterHeaders(l *zap.Logger, header *fasthttp.RequestHeader) map[string]str
 			zap.String("val", v))
 	})
 
-	return result
+	return result, err
 }
 
 func prepareExpirationHeader(headers map[string]string, epochDurations *epochDurations, now time.Time) error {
diff --git a/uploader/filter_test.go b/uploader/filter_test.go
index 585fac8..de4c541 100644
--- a/uploader/filter_test.go
+++ b/uploader/filter_test.go
@@ -16,8 +16,27 @@ import (
 func TestFilter(t *testing.T) {
 	log := zap.NewNop()
 
+	t.Run("duplicate keys error", func(t *testing.T) {
+		req := &fasthttp.RequestHeader{}
+		req.DisableNormalizing()
+		req.Add("X-Attribute-DupKey", "first-value")
+		req.Add("X-Attribute-DupKey", "second-value")
+		_, err := filterHeaders(log, req)
+		require.Error(t, err)
+	})
+
+	t.Run("duplicate system keys error", func(t *testing.T) {
+		req := &fasthttp.RequestHeader{}
+		req.DisableNormalizing()
+		req.Add("X-Attribute-Neofs-DupKey", "first-value")
+		req.Add("X-Attribute-Neofs-DupKey", "second-value")
+		_, err := filterHeaders(log, req)
+		require.Error(t, err)
+	})
+
 	req := &fasthttp.RequestHeader{}
 	req.DisableNormalizing()
+
 	req.Set("X-Attribute-Neofs-Expiration-Epoch1", "101")
 	req.Set("X-Attribute-NEOFS-Expiration-Epoch2", "102")
 	req.Set("X-Attribute-neofs-Expiration-Epoch3", "103")
@@ -30,7 +49,8 @@ func TestFilter(t *testing.T) {
 		"__NEOFS__EXPIRATION_EPOCH2": "102",
 	}
 
-	result := filterHeaders(log, req)
+	result, err := filterHeaders(log, req)
+	require.NoError(t, err)
 
 	require.Equal(t, expected, result)
 }
diff --git a/uploader/upload.go b/uploader/upload.go
index 8e65456..2effd16 100644
--- a/uploader/upload.go
+++ b/uploader/upload.go
@@ -114,7 +114,12 @@ func (u *Uploader) Upload(c *fasthttp.RequestCtx) {
 		response.Error(c, "could not receive multipart/form: "+err.Error(), fasthttp.StatusBadRequest)
 		return
 	}
-	filtered := filterHeaders(u.log, &c.Request.Header)
+	filtered, err := filterHeaders(u.log, &c.Request.Header)
+	if err != nil {
+		log.Error("could not process headers", zap.Error(err))
+		response.Error(c, err.Error(), fasthttp.StatusBadRequest)
+		return
+	}
 	if needParseExpiration(filtered) {
 		epochDuration, err := getEpochDurations(c, u.pool)
 		if err != nil {