Copy worksheet between workbooks and overwrite the current worksheet - excel

Question

I have written VBA code that opens up a destination workbook, copies one of the worksheets, and pastes it into the current workbook.
When I run it a second or third time etc... instead of overwriting the current worksheet, it creates a completely new one.
Ex: Worksheet is called "data", first time it transfers "data", second time "data(2)".
I have another worksheet that uses VLOOKUP function to look at some cells of this data worksheet, so it is crucial that it has correct name "data".
I thought about deleting the current (data) file before running the macro, but what if something crashes and I lose my worksheet? Is there a better solution?
NOTE: I am running the macro from the main workbook to get the sheet to be copied from the external workbook.
Sub UpdateT()
Dim wb As Workbook
Dim aw As Workbook
'Open 2nd Workbook
Set aw = Application.ActiveWorkbook
Set wb = Workbooks.Open(Filename:="C:\Users\yilmadu00\Desktop\T.xlsx")
'Copy To Different Workbook
wb.Sheets("data").Copy After:=aw.Sheets("Data1")
'Close 2nd Workbook
aw.Save
wb.Close
aw.Sheets("data").Visible = False
ActiveWorkbook.Protect ("Password")
End Sub

Answer 1

Function to check whether worksheet exists (credits to #ScottCrainer):
Function SheetExists(ws As String)
SheetExists = Not IsError(Application.Evaluate(ws & "!A1"))
End Function
NOTE:
It does have the issue: if A1 on the sheet contains an error it will return a false negative.

Answer 2

ActiveWorkbook vs ThisWorkbook, Sheets vs Worksheets
You have used 'Activeworkbook' and 'Sheet(s)' in the code so I played along.
But
Although you can have a third workbook to run the code from, I'm guessing you are running the code from a module in the 'ActiveWorkbook'. If this is true, it would be more correct to use 'ThisWorkbook' instead which always refers to the workbook that contains the code (module), to avoid accidentally running the code on a third workbook.
Sheet(s) refers to Worksheet(s) and Chartsheet(s), again I'm guessing there are no chartsheets involved in this code, therefore it would be more correct to use 'Worksheet(s)' instead of 'Sheet(s)'.
Sub UpdateT()
Const cStrPath As String = "C:\Users\yilmadu00\Desktop\T.xlsx"
Const cStrAfter As String = "Data1"
Const cStrName As String = "data"
Const cStrOld As String = "data_old"
Dim aw As Workbook '1st workbook, 'ActiveWorkbook'
Dim wb As Workbook '2nd workbook
Dim oWs As Sheet 'Each sheet in workbook 'aw'
Dim blnFound As Boolean 'True if sheet(cStrName) was found
Set aw = ActiveWorkbook 'Create a reference to the ActiveWorkbook
Set wb = Workbooks.Open(Filename:=cStrPath) 'Open 2nd Workbook
With aw
' .UnProtect ("Password")
'Check each sheet in workbook 'aw'.
For Each oWs In aw.Sheets
With oWs
'Check if there already is a sheet with the name 'cStrName'.
If .Name = cStrName Then
.Name = cStrOld 'Rename the sheet.
blnFound = True 'Sheet(cStrName) was found.
Exit For 'Immediately stop checking, there can only be one.
End If
End With
Next
End With
With wb
'Copy sheet from 2nd workbook ('wb') to workbook 'wa'.
.Sheets(cStrName).Copy After:=aw.Sheets(cStrAfter)
.Close 'Close 2nd workbook ('wb').
End With
With aw
With Application
If blnFound = True Then 'Sheet(cStrName) was found.
.DisplayAlerts = False 'Disable showing delete message.
aw.Sheets(cStrOld).Delete 'Delete old version of sheet.
.DisplayAlerts = True
End If
End With
.Sheets(cStrName).Visible = False 'Hide sheet named 'cStrName'
.Protect ("Password")
.Save 'Save workbook 'aw'.
End With
End Sub
The next time you want to do something with the sheet you have to unprotect it or the code will fail. Hidden sheets can be deleted with no problems.