diff --git a/README.md b/README.md
index 33df258..9dab00b 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,7 @@ The `options` object may contain the following:
   `=` character.  By default, whitespace is omitted, to be friendly to
   some persnickety old parsers that don't tolerate it well.  But some
   find that it's more human-readable and pretty with the whitespace.
+* `withoutArraySuffix` Boolean to specify whether to insert `[]` as array properties. default is `false`.
 
 For backwards compatibility reasons, if a `string` options is passed
 in, then it is assumed to be the `section` value.
diff --git a/ini.js b/ini.js
index 590195d..334dfc1 100644
--- a/ini.js
+++ b/ini.js
@@ -23,12 +23,13 @@ function encode (obj, opt) {
   }
 
   var separator = opt.whitespace ? ' = ' : '='
+  var arraySuffix = opt.withoutArraySuffix ? '' : '[]'
 
   Object.keys(obj).forEach(function (k, _, __) {
     var val = obj[k]
     if (val && Array.isArray(val)) {
       val.forEach(function (item) {
-        out += safe(k + '[]') + separator + safe(item) + '\n'
+        out += safe(k + arraySuffix) + separator + safe(item) + '\n'
       })
     } else if (val && typeof val === 'object') {
       children.push(k)
@@ -73,6 +74,11 @@ function decode (str) {
   //          section     |key      = value
   var re = /^\[([^\]]*)\]$|^([^=]+)(=(.*))?$/i
   var lines = str.split(/[\r\n]+/g)
+  // for duplicate property statist
+  var bucket = {
+    'root': {}
+  }
+  var curSection = 'root'
 
   lines.forEach(function (line, _, __) {
     if (!line || line.match(/^\s*[;#]/)) return
@@ -81,10 +87,19 @@ function decode (str) {
     if (match[1] !== undefined) {
       section = unsafe(match[1])
       p = out[section] = out[section] || {}
+      bucket[section] = bucket[section] || {}
+      curSection = section
       return
     }
     var key = unsafe(match[2])
     var value = match[3] ? unsafe(match[4]) : true
+
+    var _keyWithoutArraySuffix = key.split('[]')[0]
+    var curBucket = bucket[curSection]
+    curBucket[_keyWithoutArraySuffix] = curBucket[_keyWithoutArraySuffix] ? ++curBucket[_keyWithoutArraySuffix] : 1
+
+    if (curBucket[_keyWithoutArraySuffix] > 1) key = _keyWithoutArraySuffix + '[]'
+
     switch (value) {
       case 'true':
       case 'false':
diff --git a/test/duplicate-properties.js b/test/duplicate-properties.js
new file mode 100644
index 0000000..e7a6c7e
--- /dev/null
+++ b/test/duplicate-properties.js
@@ -0,0 +1,59 @@
+/*
+ * @Author: John Trump
+ * @Date: 2020-11-28 15:26:01
+ * @LastEditors: John Trump
+ * @LastEditTime: 2020-11-28 15:52:26
+ */
+var ini = require("../ini");
+var tap = require("tap");
+var test = tap.test;
+
+test("decode with duplicate properties", function(t) {
+  var d = ini.decode(`
+  zr[] = deedee;
+  zr=123;
+  ar[] = one
+  ar[] = three;
+  str = 3;
+  brr = 1;
+  brr = 2;
+  brr = 3;
+  brr = 3;`);
+  t.deepEqual(d, {
+    zr: ["deedee", "123"],
+    ar: ["one", "three"],
+    str: "3",
+    brr: ["1", "2", "3", "3"],
+  });
+  t.end();
+});
+
+test("encode with duplicate properties", function(t) {
+  var d = ini.encode({
+    ar: ["1", "2", "3"],
+    br: ["1", "2"],
+  });
+  var excepted = 'ar[]=1\n'
+               + 'ar[]=2\n'
+               + 'ar[]=3\n'
+               + 'br[]=1\n'
+               + 'br[]=2\n'
+  t.deepEqual(d, excepted)
+  t.end();
+});
+
+test("encode with option with duplicate properties", function(t) {
+  var d = ini.encode({
+    ar: ["1", "2", "3"],
+    br: ["1", "2"],
+  }, {
+    withoutArraySuffix: true
+  });
+  var excepted = 'ar=1\n'
+               + 'ar=2\n'
+               + 'ar=3\n'
+               + 'br=1\n'
+               + 'br=2\n'
+  t.deepEqual(d, excepted)
+  t.end();
+});
\ No newline at end of file
diff --git a/test/fixtures/foo.ini b/test/fixtures/foo.ini
index fc2080f..2745e05 100644
--- a/test/fixtures/foo.ini
+++ b/test/fixtures/foo.ini
@@ -25,7 +25,7 @@ ar[] = three
 ; This should be included in the array
 ar   = this is included
 
-; Test resetting of a value (and not turn it into an array)
+; Test resetting of a value (turn it into an array)
 br = cold
 br = warm
 
@@ -63,3 +63,10 @@ nocomment = this\; this is not a comment
 
 # this next one is not a comment!  it's escaped!
 noHashComment = this\# this is not a comment
+
+[duplicate]
+ar = 1
+ar = 2
+ar[] = 3
+br = 1;
+br = 2;
\ No newline at end of file
diff --git a/test/foo.js b/test/foo.js
index 58102d1..742ec57 100644
--- a/test/foo.js
+++ b/test/foo.js
@@ -17,7 +17,8 @@ var i = require("../")
             + 'ar[]=one\n'
             + 'ar[]=three\n'
             + 'ar[]=this is included\n'
-            + 'br=warm\n'
+            + 'br[]=cold\n'
+            + 'br[]=warm\n'
             + 'eq=\"eq=eq\"\n'
             + '\n'
             + '[a]\n'
@@ -33,6 +34,13 @@ var i = require("../")
             + '[x\\.y\\.z.a\\.b\\.c]\na.b.c=abc\n'
             + 'nocomment=this\\; this is not a comment\n'
             + 'noHashComment=this\\# this is not a comment\n'
+            + '\n'
+            + '[duplicate]\n'
+            + 'ar[]=1\n'
+            + 'ar[]=2\n'
+            + 'ar[]=3\n'
+            + 'br[]=1\n'
+            + 'br[]=2\n'
   , expectD =
     { o: 'p',
       'a with spaces': 'b  c',
@@ -43,7 +51,7 @@ var i = require("../")
       's2': 'something else',
       'zr': ['deedee'],
       'ar': ['one', 'three', 'this is included'],
-      'br': 'warm',
+      'br': ['cold', 'warm'],
       'eq': 'eq=eq',
       a:
        { av: 'a val',
@@ -59,6 +67,10 @@ var i = require("../")
           'nocomment': 'this\; this is not a comment',
           noHashComment: 'this\# this is not a comment'
         }
+      },
+      duplicate: {
+        ar: ["1", "2", "3"],
+        br: ["1", "2"]
       }
     }
   , expectF = '[prefix.log]\n'