Option Explicit
Private Sub Worksheet_Activate()
With Selection.Resize(, 2): .Merge: .Select: End With
End Sub
Private Sub Worksheet_BeforeDoubleClick(ByVal c As Range, Cancel As Boolean)
Dim où As Range
c.MergeCells = False
c(1, 1).Select
Set où = Sheets("Feuil2").Cells.Find(Selection.Value, LookIn:=xlValues)
If Not où Is Nothing Then Sheets("Feuil2").Activate: où.Select
End Sub