fix(kit): clone middleware when adding to app

packages/kit/src/pages.ts

@@ -53,12 +53,12 @@ export function addRouteMiddleware (input: NuxtMiddleware | NuxtMiddleware[], op
       if (find >= 0) {
         if (app.middleware[find].path === middleware.path) { continue }
         if (options.override === true) {
-          app.middleware[find] = middleware
+          app.middleware[find] = { ...middleware }
         } else {
           logger.warn(`'${middleware.name}' middleware already exists at '${app.middleware[find].path}'. You can set \`override: true\` to replace it.`)
         }
       } else {
-        app.middleware.push(middleware)
+        app.middleware.push({ ...middleware })
       }
     }
   })