#include <Date.au3>
$sFile1 = @DesktopDir & "\file1.txt"
$sFile2 = @DesktopDir & "\file2.txt"
$sDateDiff_Pattern = "(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})"
$sFileTime1 = StringRegExpReplace(FileGetTime($sFile1, 0, 1), $sDateDiff_Pattern, "\1/\2/\3 \4:\5:\6")
$sFileTime2 = StringRegExpReplace(FileGetTime($sFile2, 0, 1), $sDateDiff_Pattern, "\1/\2/\3 \4:\5:\6")
If _DateDiff("s", $sFileTime1, $sFileTime2) > 0 Then
$sFile = $sFile2
$sFileTime = $sFileTime2
Else
$sFile = $sFile1
$sFileTime = $sFileTime1
EndIf
MsgBox(64, 'Title', 'Файл <' & StringRegExpReplace($sFile, "^.*\\", "") & '> изменён позже (' & $sFileTime & ').')