diff --git a/ctx.go b/ctx.go
index 8e568e2576..880113d5f2 100644
--- a/ctx.go
+++ b/ctx.go
@@ -651,10 +651,11 @@ func (c *Ctx) GetRespHeader(key string, defaultValue ...string) string {
 // GetReqHeaders returns the HTTP request headers.
 // Returned value is only valid within the handler. Do not store any references.
 // Make copies or use the Immutable setting instead.
-func (c *Ctx) GetReqHeaders() map[string]string {
-	headers := make(map[string]string)
+func (c *Ctx) GetReqHeaders() map[string][]string {
+	headers := make(map[string][]string)
 	c.Request().Header.VisitAll(func(k, v []byte) {
-		headers[c.app.getString(k)] = c.app.getString(v)
+		key := c.app.getString(k)
+		headers[key] = append(headers[key], c.app.getString(v))
 	})
 
 	return headers
@@ -663,10 +664,11 @@ func (c *Ctx) GetReqHeaders() map[string]string {
 // GetRespHeaders returns the HTTP response headers.
 // Returned value is only valid within the handler. Do not store any references.
 // Make copies or use the Immutable setting instead.
-func (c *Ctx) GetRespHeaders() map[string]string {
-	headers := make(map[string]string)
+func (c *Ctx) GetRespHeaders() map[string][]string {
+	headers := make(map[string][]string)
 	c.Response().Header.VisitAll(func(k, v []byte) {
-		headers[c.app.getString(k)] = c.app.getString(v)
+		key := c.app.getString(k)
+		headers[key] = append(headers[key], c.app.getString(v))
 	})
 
 	return headers
diff --git a/ctx_test.go b/ctx_test.go
index 7e89327ff8..ae15febef9 100644
--- a/ctx_test.go
+++ b/ctx_test.go
@@ -5117,12 +5117,39 @@ func Test_Ctx_GetRespHeaders(t *testing.T) {
 
 	c.Set("test", "Hello, World 👋!")
 	c.Set("foo", "bar")
+	c.Response().Header.Set("multi", "one")
+	c.Response().Header.Add("multi", "two")
 	c.Response().Header.Set(HeaderContentType, "application/json")
 
-	utils.AssertEqual(t, c.GetRespHeaders(), map[string]string{
-		"Content-Type": "application/json",
-		"Foo":          "bar",
-		"Test":         "Hello, World 👋!",
+	utils.AssertEqual(t, c.GetRespHeaders(), map[string][]string{
+		"Content-Type": {"application/json"},
+		"Foo":          {"bar"},
+		"Multi":        {"one", "two"},
+		"Test":         {"Hello, World 👋!"},
+	})
+}
+
+func Benchmark_Ctx_GetRespHeaders(b *testing.B) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+
+	c.Response().Header.Set("test", "Hello, World 👋!")
+	c.Response().Header.Set("foo", "bar")
+	c.Response().Header.Set(HeaderContentType, "application/json")
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	var headers map[string][]string
+	for n := 0; n < b.N; n++ {
+		headers = c.GetRespHeaders()
+	}
+
+	utils.AssertEqual(b, headers, map[string][]string{
+		"Content-Type": {"application/json"},
+		"Foo":          {"bar"},
+		"Test":         {"Hello, World 👋!"},
 	})
 }
 
@@ -5133,14 +5160,41 @@ func Test_Ctx_GetReqHeaders(t *testing.T) {
 	c := app.AcquireCtx(&fasthttp.RequestCtx{})
 	defer app.ReleaseCtx(c)
 
+	c.Request().Header.Set("test", "Hello, World 👋!")
+	c.Request().Header.Set("foo", "bar")
+	c.Request().Header.Set("multi", "one")
+	c.Request().Header.Add("multi", "two")
+	c.Request().Header.Set(HeaderContentType, "application/json")
+
+	utils.AssertEqual(t, c.GetReqHeaders(), map[string][]string{
+		"Content-Type": {"application/json"},
+		"Foo":          {"bar"},
+		"Test":         {"Hello, World 👋!"},
+		"Multi":        {"one", "two"},
+	})
+}
+
+func Benchmark_Ctx_GetReqHeaders(b *testing.B) {
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	defer app.ReleaseCtx(c)
+
 	c.Request().Header.Set("test", "Hello, World 👋!")
 	c.Request().Header.Set("foo", "bar")
 	c.Request().Header.Set(HeaderContentType, "application/json")
 
-	utils.AssertEqual(t, c.GetReqHeaders(), map[string]string{
-		"Content-Type": "application/json",
-		"Foo":          "bar",
-		"Test":         "Hello, World 👋!",
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	var headers map[string][]string
+	for n := 0; n < b.N; n++ {
+		headers = c.GetReqHeaders()
+	}
+
+	utils.AssertEqual(b, headers, map[string][]string{
+		"Content-Type": {"application/json"},
+		"Foo":          {"bar"},
+		"Test":         {"Hello, World 👋!"},
 	})
 }
 
diff --git a/docs/api/ctx.md b/docs/api/ctx.md
index 1da3db9795..fdd473aacc 100644
--- a/docs/api/ctx.md
+++ b/docs/api/ctx.md
@@ -554,7 +554,7 @@ app.Get("/", func(c *fiber.Ctx) error {
 Returns the HTTP request headers.
 
 ```go title="Signature"
-func (c *Ctx) GetReqHeaders() map[string]string
+func (c *Ctx) GetReqHeaders() map[string][]string
 ```
 
 > _Returned value is only valid within the handler. Do not store any references.  
@@ -589,7 +589,7 @@ app.Get("/", func(c *fiber.Ctx) error {
 Returns the HTTP response headers.
 
 ```go title="Signature"
-func (c *Ctx) GetRespHeaders() map[string]string
+func (c *Ctx) GetRespHeaders() map[string][]string
 ```
 
 > _Returned value is only valid within the handler. Do not store any references.  
diff --git a/middleware/idempotency/idempotency.go b/middleware/idempotency/idempotency.go
index ae4097ae9d..604f867c76 100644
--- a/middleware/idempotency/idempotency.go
+++ b/middleware/idempotency/idempotency.go
@@ -45,8 +45,10 @@ func New(config ...Config) fiber.Handler {
 
 			_ = c.Status(res.StatusCode)
 
-			for header, val := range res.Headers {
-				c.Set(header, val)
+			for header, vals := range res.Headers {
+				for _, val := range vals {
+					c.Context().Response.Header.Add(header, val)
+				}
 			}
 
 			if len(res.Body) != 0 {
@@ -122,7 +124,7 @@ func New(config ...Config) fiber.Handler {
 				res.Headers = headers
 			} else {
 				// Filter
-				res.Headers = make(map[string]string)
+				res.Headers = make(map[string][]string)
 				for h := range headers {
 					if _, ok := keepResponseHeadersMap[utils.ToLower(h)]; ok {
 						res.Headers[h] = headers[h]
diff --git a/middleware/idempotency/response.go b/middleware/idempotency/response.go
index ca06bcb452..f42d1a3311 100644
--- a/middleware/idempotency/response.go
+++ b/middleware/idempotency/response.go
@@ -4,7 +4,7 @@ package idempotency
 type response struct {
 	StatusCode int `msg:"sc"`
 
-	Headers map[string]string `msg:"hs"`
+	Headers map[string][]string `msg:"hs"`
 
 	Body []byte `msg:"b"`
 }
diff --git a/middleware/idempotency/response_msgp.go b/middleware/idempotency/response_msgp.go
index 4eb4d7fcb0..410d118ca0 100644
--- a/middleware/idempotency/response_msgp.go
+++ b/middleware/idempotency/response_msgp.go
@@ -18,7 +18,10 @@ func (z *response) MarshalMsg(b []byte) (o []byte, err error) {
 	o = msgp.AppendMapHeader(o, uint32(len(z.Headers)))
 	for za0001, za0002 := range z.Headers {
 		o = msgp.AppendString(o, za0001)
-		o = msgp.AppendString(o, za0002)
+		o = msgp.AppendArrayHeader(o, uint32(len(za0002)))
+		for za0003 := range za0002 {
+			o = msgp.AppendString(o, za0002[za0003])
+		}
 	}
 	// string "b"
 	o = append(o, 0xa1, 0x62)
@@ -58,7 +61,7 @@ func (z *response) UnmarshalMsg(bts []byte) (o []byte, err error) {
 				return
 			}
 			if z.Headers == nil {
-				z.Headers = make(map[string]string, zb0002)
+				z.Headers = make(map[string][]string, zb0002)
 			} else if len(z.Headers) > 0 {
 				for key := range z.Headers {
 					delete(z.Headers, key)
@@ -66,18 +69,31 @@ func (z *response) UnmarshalMsg(bts []byte) (o []byte, err error) {
 			}
 			for zb0002 > 0 {
 				var za0001 string
-				var za0002 string
+				var za0002 []string
 				zb0002--
 				za0001, bts, err = msgp.ReadStringBytes(bts)
 				if err != nil {
 					err = msgp.WrapError(err, "Headers")
 					return
 				}
-				za0002, bts, err = msgp.ReadStringBytes(bts)
+				var zb0003 uint32
+				zb0003, bts, err = msgp.ReadArrayHeaderBytes(bts)
 				if err != nil {
 					err = msgp.WrapError(err, "Headers", za0001)
 					return
 				}
+				if cap(za0002) >= int(zb0003) {
+					za0002 = (za0002)[:zb0003]
+				} else {
+					za0002 = make([]string, zb0003)
+				}
+				for za0003 := range za0002 {
+					za0002[za0003], bts, err = msgp.ReadStringBytes(bts)
+					if err != nil {
+						err = msgp.WrapError(err, "Headers", za0001, za0003)
+						return
+					}
+				}
 				z.Headers[za0001] = za0002
 			}
 		case "b":
@@ -104,7 +120,10 @@ func (z *response) Msgsize() (s int) {
 	if z.Headers != nil {
 		for za0001, za0002 := range z.Headers {
 			_ = za0002
-			s += msgp.StringPrefixSize + len(za0001) + msgp.StringPrefixSize + len(za0002)
+			s += msgp.StringPrefixSize + len(za0001) + msgp.ArrayHeaderSize
+			for za0003 := range za0002 {
+				s += msgp.StringPrefixSize + len(za0002[za0003])
+			}
 		}
 	}
 	s += 2 + msgp.BytesPrefixSize + len(z.Body)
diff --git a/middleware/logger/tags.go b/middleware/logger/tags.go
index 87b9a9b228..67ccbb83a2 100644
--- a/middleware/logger/tags.go
+++ b/middleware/logger/tags.go
@@ -102,7 +102,7 @@ func createTagMap(cfg *Config) map[string]LogFunc {
 		TagReqHeaders: func(output Buffer, c *fiber.Ctx, data *Data, extraParam string) (int, error) {
 			reqHeaders := make([]string, 0)
 			for k, v := range c.GetReqHeaders() {
-				reqHeaders = append(reqHeaders, k+"="+v)
+				reqHeaders = append(reqHeaders, k+"="+strings.Join(v, ","))
 			}
 			return output.Write([]byte(strings.Join(reqHeaders, "&")))
 		},