How to merge 2 Function on Apps script

How to merge multiple function for apps script ?
I Try learn from google but I can’t find solution
help me please, Thank you very munch.

var ss = SpreadsheetApp.openByUrl("Test1");
var ss = SpreadsheetApp.openByUrl("Test2");
var sheet = ss.getSheetByName("Product");
var member = ss.getSheetByName("Member");

function doPost(e) {

  var data = JSON.parse(e.postData.contents)
  var userMsg = data.originalDetectIntentRequest.payload.data.message.text;
  var values = sheet.getRange(2, 3, sheet.getLastRow(), sheet.getLastColumn()).getValues();
  for (var i = 0; i < values.length; i++) {

    if (values[i][0] == userMsg) {
      i = i + 2;
      var Product = sheet.getRange(i, 3).getValue(); //Product
      var Data1 = sheet.getRange(i, 4).getValue(); //Price
      var Data2 = sheet.getRange(i, 5).getValue(); //Size
      var Data3 = sheet.getRange(i, 1).getValue(); //Book Name

      var result = {
        "fulfillmentMessages": [{
          "type": "text",
          "text": "Price : " + Data1 + " ฿"
        }, ]
      }

      var replyJSON = ContentService.createTextOutput(JSON.stringify(result)).setMimeType(ContentService.MimeType.JSON);
      return replyJSON;
    }
  }
}

function doPost(e) {

  var diaflow = JSON.parse(e.postData.contents)
  var userMsg = diaflow.originalDetectIntentRequest.payload.data.message.text;
  var valuess = member.getRange(2, 3, member.getLastRow(), member.getLastColumn()).getValues();
  for (var i = 0; i < valuess.length; i++) {

    if (valuess[i][0] == userMsg) {
      i = i + 2;
      var Product = member.getRange(i, 3).getValue(); //Product
      var Data1 = member.getRange(i, 4).getValue(); //Price
      var Data2 = member.getRange(i, 5).getValue(); //Size
      var Data3 = member.getRange(i, 1).getValue(); //Book Name

      var result = {
        "fulfillmentMessages": [{
          "type": "text",
          "text": "Price : " + Data1 + " ฿"
        }, ]
      }

      var replyJSON = ContentService.createTextOutput(JSON.stringify(result)).setMimeType(ContentService.MimeType.JSON);
      return replyJSON;
    }
  }
}

How to merge multiple function for apps script ?
How to use multiple function because i use this code can run one function only.