# panic: grpc: Server.RegisterService 发现服务 "pb.UserService" 重复注册

- **ID:** `go/grpc-already-exists-duplicate-register`
- **领域:** go
- **类别:** runtime_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

同一个 gRPC 服务被注册到同一 grpc.Server 两次，通常来自多个包中的 init() 函数，或初始化时两次调用 RegisterXServer。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| google.golang.org/grpc 1.50+ | active | — | — |

## 解决方案

1. **** (95% 成功率)
   ```
   func RegisterAll(s *grpc.Server) {
    pb.RegisterUserServiceServer(s, &userServer{})
    pb.RegisterOrderServiceServer(s, &orderServer{})
}
// call exactly once from main
   ```
2. **** (90% 成功率)
   ```
   // delete func init() { pb.RegisterUserServiceServer(...) }
// replace with explicit call in main()
   ```

## 无效尝试

- **** — The server is left in an inconsistent state; subsequent calls may hit the wrong handler or panic again. (85% 失败率)
- **** — Two servers on the same listener cause bind errors or split traffic unpredictably. (70% 失败率)