这个问题常常是因为AWS的nodejs sdk没有正确的关闭websocket连接而导致的。可以通过以下代码解决：

const AWS = require('aws-sdk');
const apigatewaymanagementapi = new AWS.ApiGatewayManagementApi({
  apiVersion: '2018-11-29',
  endpoint: 'https://' + process.env.APIGATEWAY_WEBSOCKET_ENDPOINT + '/' + process.env.STAGE,
  accessKeyId: process.env.AWS_ACCESS_KEY_ID,
  secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  sessionToken: process.env.AWS_SESSION_TOKEN
});

class WebSocketClient {
  static async sendMessage(connectionId, data) {
    try {
      await apigatewaymanagementapi.postToConnection({
        ConnectionId: connectionId,
        Data: data
      }).promise();
    } catch (error) {
      if (error.statusCode === 410) {
        console.warn(`Connection ${connectionId} is gone`);
      } else {
        console.error(`Failed to send message to ${connectionId}: `, error);
      }
    } finally {
      // Cleanup
      await apigatewaymanagementapi._cleanup()
    }
  }
}

apigatewaymanagementapi._cleanup = async function() {
  return new Promise((resolve, reject) => {
    if (this.ws && this.ws.terminate) {
      this.ws.terminate();
    }
    this.ws = null;
    resolve();
  });
}

在你调用AWS.ApiGatewayManagementApi.postToConnection()之后加上一句await apigatewaymanagementapi._cleanup()，用来关闭websocket连接。这样就能解决调用一次却执行两次的问题了。