Nit: Dedupe languages

src/overlay/caching.test.ts

@@ -391,6 +391,32 @@ test.serial(
   },
 );
 
+test.serial(
+  "getCodeQlVersionsForOverlayBaseDatabases de-duplicates resolved language aliases",
+  async (t) => {
+    const logger = getRunnerLogger(true);
+
+    sinon.stub(apiClient, "getAutomationID").resolves("test-automation-id/");
+    const listActionsCachesStub = sinon
+      .stub(apiClient, "listActionsCaches")
+      .resolves([
+        {
+          key: "codeql-overlay-base-database-1-c5666c509a2d9895-javascript_python-2.25.0-abc123-1-1",
+        },
+      ]);
+
+    const result = await getCodeQlVersionsForOverlayBaseDatabases(
+      ["javascript", "typescript", "Python", "python"],
+      logger,
+    );
+    t.deepEqual(result, ["2.25.0"]);
+    sinon.assert.calledOnceWithExactly(
+      listActionsCachesStub,
+      "codeql-overlay-base-database-1-c5666c509a2d9895-javascript_python-",
+    );
+  },
+);
+
 test.serial(
   "getCodeQlVersionsForOverlayBaseDatabases ignores nightly versions with build metadata",
   async (t) => {

src/overlay/caching.ts

@@ -461,9 +461,10 @@ export async function getCodeQlVersionsForOverlayBaseDatabases(
     );
     return undefined;
   }
-  const cacheKeyPrefix = await getCacheKeyPrefixBase(
-    languages.filter((l) => l !== undefined),
-  );
+  const dedupedLanguages = [
+    ...new Set(languages.filter((l) => l !== undefined)),
+  ];
+  const cacheKeyPrefix = await getCacheKeyPrefixBase(dedupedLanguages);
 
   logger.debug(
     `Searching for overlay-base databases in Actions cache with ` +