Maybe this would do it but I doubt the left positions you ask for are what you need!

Sub fixPH()

Dim oshp1 As Shape
Dim oshp2 As Shape
Dim osld As Slide
Dim L As Long
Dim b_continue As Boolean
For Each osld In ActivePresentation.Slides
For L = 1 To osld.Shapes.Count
If osld.Shapes(L).Type = msoPlaceholder Then
If osld.Shapes(L).PlaceholderFormat.ContainedType = msoPicture Then
If Not b_continue Then
Set oshp1 = osld.Shapes(L)
b_continue = True
Else
Set oshp2 = osld.Shapes(L)
End If
End If
End If
Next L
If oshp1.Left < oshp2.Left Then
oshp1.LockAspectRatio = True
oshp1.Height = 4.5 * 72
oshp1.Left = 2.3 * 72
oshp1.Top = 2.83 * 72
oshp2.LockAspectRatio = True
oshp2.Height = 4.5 * 72
oshp2.Left = 7.86 * 72
oshp2.Top = 2.83 * 72
Else
oshp2.LockAspectRatio = True
oshp2.Height = 4.5 * 72
oshp2.Left = 2.3 * 72
oshp2.Top = 2.83 * 72
oshp1.LockAspectRatio = True
oshp1.Height = 4.5 * 72
oshp1.Left = 7.86 * 72
oshp1.Top = 2.83 * 72
End If
b_continue = False
Next osld
End Sub