Maybe you could try this ...
Option Explicit
Sub clashCheck()
Dim cel As Range, rng As Range, concV As String, lastR As Long, _
ckRng As Range, msg As String
lastR = Range("A65536").End(xlUp).Row
Columns(1).Insert
Range("A5:A" & lastR).Formula = "=D5&CHAR(224)&E5"
Set ckRng = Range("A5:A" & lastR)
Set rng = Range("D5:D" & lastR)
For Each cel In rng
concV = cel.Value & Chr(224) & cel.Offset(, 1).Value
If WorksheetFunction.CountIf(ckRng, concV) > 1 Then
msg = msg & "Equipment: " & cel.Value & ", on row " & cel.Row & " has a clash." & vbCr
End If
skipMe:
Next cel
Columns(1).Delete
If msg <> "" Then
MsgBox msg
Exit Sub
End If
MsgBox "No clashes were found!", vbOKOnly + vbInformation, "No Clashes!"
End Sub
Not sure if it's exactly what you're looking for. Post back any additional needed details. Example workbook attached. HTH