diff --git a/versions/3.1.0.md b/versions/3.1.0.md
index f0c7f54abe..00b4a366f0 100644
--- a/versions/3.1.0.md
+++ b/versions/3.1.0.md
@@ -841,7 +841,7 @@ Describes a single API operation on a path.
 
 Field Name | Type | Description
 ---|:---:|---
-<a name="operationTags"></a>tags | [`string`] | A list of tags for API documentation control. Tags can be used for logical grouping of operations by resources or any other qualifier.
+<a name="operationTags"></a>tags | [`string`] | A list of tags for API documentation control. Tags can be used for logical grouping of operations by resources or any other qualifier. Duplicate tags MAY be considered an authoring mistake.
 <a name="operationSummary"></a>summary | `string` | A short summary of what the operation does.
 <a name="operationDescription"></a>description | `string` | A verbose explanation of the operation behavior. [CommonMark syntax](http://spec.commonmark.org/) MAY be used for rich text representation.
 <a name="operationExternalDocs"></a>externalDocs | [External Documentation Object](#externalDocumentationObject) | Additional external documentation for this operation.