diff --git a/quartz/plugins/transformers/frontmatter.ts b/quartz/plugins/transformers/frontmatter.ts
index c04c52a..ce57428 100644
--- a/quartz/plugins/transformers/frontmatter.ts
+++ b/quartz/plugins/transformers/frontmatter.ts
@@ -114,6 +114,10 @@ export const FrontMatter: QuartzTransformerPlugin<Partial<Options>> = (userOpts)
 
             if (socialImage) data.socialImage = socialImage
 
+            // Remove duplicate slugs
+            const uniqueSlugs = [...new Set(allSlugs)]
+            allSlugs.splice(0, allSlugs.length, ...uniqueSlugs)
+
             // fill in frontmatter
             file.data.frontmatter = data as QuartzPluginData["frontmatter"]
           }