diff --git a/index.js b/index.js
index 2f14dd0..836b4c7 100644
--- a/index.js
+++ b/index.js
@@ -10,6 +10,10 @@ function SerializerSelector () {
 }
 
 function responseSchemaCompiler (fjsOpts, { schema /* method, url, httpStatus */ }) {
+  if (fjsOpts.schema && schema.$id && fjsOpts.schema[schema.$id]) {
+    fjsOpts.schema = { ...fjsOpts.schema }
+    delete fjsOpts.schema[schema.$id]
+  }
   return fastJsonStringify(schema, fjsOpts)
 }
 
diff --git a/test/duplicate-schema.test.js b/test/duplicate-schema.test.js
new file mode 100644
index 0000000..d6904ed
--- /dev/null
+++ b/test/duplicate-schema.test.js
@@ -0,0 +1,26 @@
+'use strict'
+
+const t = require('tap')
+const FjsCompiler = require('../index')
+
+t.test('Use input schema duplicate in the externalSchemas', async t => {
+  t.plan(1)
+  const externalSchemas = {
+    schema1: {
+      $id: 'schema1',
+      type: 'number'
+    },
+    schema2: {
+      $id: 'schema2',
+      type: 'string'
+    }
+  }
+
+  const factory = FjsCompiler()
+  const compiler = factory(externalSchemas)
+
+  compiler({ schema: externalSchemas.schema1 })
+  compiler({ schema: externalSchemas.schema2 })
+
+  t.pass()
+})