I answered question with this WORK code:
This vba code will go through all identifiers from the bottom up, if the fax number already exists, it will add the identifier to this row in columns C, D, E, etc. (always choosing the next empty one) and then delete the line. In the end, it replaces columns A and B, so you are left with the fax number in Col A and Cols B, C, D, E, etc. ALL IDS associated with this number.
Tested work:
Sub RemoveDups()
Dim CurRow As Long, LastRow As Long, DestLast As Long, DestRng As Range
LastRow = Range("A" & Rows.Count).End(xlUp).Row
On Error Resume Next
For CurRow = LastRow To 3 Step -1
Set DestRng = Range("B2:B" & CurRow - 1).Find(Range("B" & CurRow).Value, LookIn:=xlValues, LookAt:=xlWhole, SearchDirection:=xlNext)
DestRng = DestRng
If Err > 0 Then
Err.Clear
Else
DestLast = Cells(DestRng.Row, Columns.Count).End(xlToLeft).Column + 1
Cells(DestRng.Row, DestLast).Value = Cells(CurRow, 1).Value
Cells(CurRow, 1).EntireRow.Delete xlShiftUp
End If
Next CurRow
Columns("B:B").Cut
Columns("A:A").Insert Shift:=xlToRight
Application.CutCopyMode = False
MsgBox "Done"
End Sub
: DestRng = DestRng? , , , , DestRng Cells.Value. , , DestRng = DestRng, , , . , . , Range.Find() , DestRng = DestRng .
EDIT: :
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DestRng = DestRng EntireRow.Delete : 
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