diff --git a/.changeset/slimy-points-learn.md b/.changeset/slimy-points-learn.md
new file mode 100644
index 000000000..1d664486d
--- /dev/null
+++ b/.changeset/slimy-points-learn.md
@@ -0,0 +1,5 @@
+---
+"openapi-typescript": patch
+---
+
+fix: replace special characters using `SPECIAL_CHARACTER_MAP` for duplicate-identifiers
diff --git a/packages/openapi-typescript/src/lib/ts.ts b/packages/openapi-typescript/src/lib/ts.ts
index c090a2eac..e658e2680 100644
--- a/packages/openapi-typescript/src/lib/ts.ts
+++ b/packages/openapi-typescript/src/lib/ts.ts
@@ -4,6 +4,10 @@ import ts, { type LiteralTypeNode, type TypeLiteralNode } from "typescript";
 export const JS_PROPERTY_INDEX_RE = /^[A-Za-z_$][A-Za-z_$0-9]*$/;
 export const JS_ENUM_INVALID_CHARS_RE = /[^A-Za-z_$0-9]+(.)?/g;
 export const JS_PROPERTY_INDEX_INVALID_CHARS_RE = /[^A-Za-z_$0-9]+/g;
+export const SPECIAL_CHARACTER_MAP: Record<string, string> = {
+  "+": "Plus",
+  // Add more mappings as needed
+};
 
 export const BOOLEAN = ts.factory.createKeywordTypeNode(ts.SyntaxKind.BooleanKeyword);
 export const FALSE = ts.factory.createLiteralTypeNode(ts.factory.createFalse());
@@ -308,7 +312,9 @@ export function tsEnumMember(value: string | number, metadata: { name?: string;
       if (invalidCharMatch[0] === name) {
         name = `"${name}"`;
       } else {
-        name = name.replace(JS_PROPERTY_INDEX_INVALID_CHARS_RE, "_");
+        name = name.replace(JS_PROPERTY_INDEX_INVALID_CHARS_RE, (s) => {
+          return s in SPECIAL_CHARACTER_MAP ? SPECIAL_CHARACTER_MAP[s] : "_";
+        });
       }
     }
   }
diff --git a/packages/openapi-typescript/test/lib/ts.test.ts b/packages/openapi-typescript/test/lib/ts.test.ts
index 517a00d58..d6169181d 100644
--- a/packages/openapi-typescript/test/lib/ts.test.ts
+++ b/packages/openapi-typescript/test/lib/ts.test.ts
@@ -208,6 +208,14 @@ describe("tsEnum", () => {
     NotFound = 101,
     // User doesn't have permissions
     PermissionDenied = 102
+}`);
+  });
+
+  test("replace special character", () => {
+    expect(astToString(tsEnum("FOO_ENUM", ["Etc/GMT+0", "Etc/GMT+1", "Etc/GMT-1"])).trim()).toBe(`enum FOO_ENUM {
+    Etc_GMTPlus0 = "Etc/GMT+0",
+    Etc_GMTPlus1 = "Etc/GMT+1",
+    Etc_GMT_1 = "Etc/GMT-1"
 }`);
   });
 });