diff --git a/index.js b/index.js
index 5e905521..b1e8135a 100644
--- a/index.js
+++ b/index.js
@@ -9,6 +9,7 @@ const pipe = fns => x => fns.reduce((result, fn) => fn(result), x)
 const onArray = fn => x => (Array.isArray(x) ? fn(x) : x)
 const uniq = onArray(xs => xs.filter((x, i) => i === xs.indexOf(x)))
 const sortArray = onArray(array => [...array].sort())
+const uniqAndSortArray = pipe([uniq, sortArray])
 const isPlainObject = x =>
   x && Object.prototype.toString.call(x) === '[object Object]'
 const onObject = fn => x => (isPlainObject(x) ? fn(x) : x)
@@ -195,10 +196,10 @@ const fields = [
   { key: 'devDependencies', over: sortObject },
   { key: 'peerDependencies', over: sortObject },
   { key: 'optionalDependencies', over: sortObject },
-  { key: 'bundledDependencies', over: sortArray },
-  { key: 'bundleDependencies', over: sortArray },
-  /* vscode */ { key: 'extensionPack', over: sortArray },
-  /* vscode */ { key: 'extensionDependencies', over: sortArray },
+  { key: 'bundledDependencies', over: uniqAndSortArray },
+  { key: 'bundleDependencies', over: uniqAndSortArray },
+  /* vscode */ { key: 'extensionPack', over: uniqAndSortArray },
+  /* vscode */ { key: 'extensionDependencies', over: uniqAndSortArray },
   { key: 'flat' },
   { key: 'engines', over: sortObject },
   { key: 'engineStrict', over: sortObject },
diff --git a/test.js b/test.js
index 2adbab5b..b770560d 100644
--- a/test.js
+++ b/test.js
@@ -608,8 +608,9 @@ for (const field of [
 ]) {
   testField(field, [
     {
-      value: ['z', 'a'],
+      value: ['z', 'a', 'a'],
       expect: ['a', 'z'],
+      message: `Should sort and unique array type of ${field} field.`,
     },
     // should ignore object
     {