How to look for duplicates in first column, then copy / paste contents of second column?

Hello speedyhub,

Finally I've created code for You - follow below points
1. sort your source array regarding ID
2. use provided procedure (copy it into module or to source code of your sheet)
3. use autofilter for get expected result

Sub GiveMeTransposeResult()
'Author: MaczaQ
Dim sAddr As String, source, tmp, cl As Range, colOffset as Integer
 
Set source = Range("A3:B20")  '<<<<------------------------------SOURCE-------------------------------------
'other way to set up source range if you want to select your source data just unhash below code
'Set source = Selection
colOffset = source.Columns.Count
 
  With source.Columns(1)
    Set tmp = .Cells(1, 1)
     For Each cl In .Cells
        'all groups excluding last group
        If cl.Value <> tmp.Value And cl.Address <> .Cells(.Cells.Count, 1).Address Then
          sAddr = tmp.Address & ":" & cl.Offset(-1).Address
           arr = Application.Transpose(Range(sAddr).Offset(, 1))
             If tmp.Address <> cl.Offset(-1).Address Then
               Range(tmp.Address).Offset(, colOffset).Resize(, UBound(arr)).Value = arr
             Else
               Range(tmp.Address).Offset(, colOffset).Value = arr
             End If
           Set tmp = cl
        End If
       
        'last group
        If cl.Address = .Cells(.Cells.Count, 1).Address Then
         sAddr = tmp.Address & ":" & cl.Address
           arr = Application.Transpose(Range(sAddr).Offset(, 1))
             If tmp.Address <> cl.Offset(-1).Address Then
                Range(tmp.Address).Offset(, colOffset).Resize(, UBound(arr)).Value = arr
             Else
                Range(tmp.Address).Offset(, colOffset).Value = arr
             End If
        End If
     Next cl
  End With
End Sub

If you will need any more help do not hasitate to post it.