Dim strtextfile As String
Dim strtextfile1 As String
Dim strtextfile2 As String
Dim strtextfile3 As String
Dim lines() as String
dim logic as boolean
dim duplicate as string
dim nonduplicate as string

hfile = FreeFile

Open "file1.txt" For Input As #hfile
strtextfile1 = Input$(LOF(hfile), hfile)
Close #hfile

hfile = FreeFile

Open "file2.txt" For Input As #hfile
strtextfile2 = Input$(LOF(hfile), hfile)
Close #hfile

hfile = FreeFile

Open "file3.txt" For Input As #hfile
strtextfile3 = Input$(LOF(hfile), hfile)
Close #hfile

' and so on until 5
' after than concatenate them into a single file
strtextfile=strtextfile1 & vbcrlf & strtextfile2 & vbcrlf & strtextfile3

' after that split the string by the vbcrlf character (newline)
lines=split(strtextfile,vbcrlf)

' then check each value to see if it's a duplicate
for i=0 to ubound(lines)-1
     logic=true
     for j=i+1 to ubound(lines)
         if lines(i)=lines(j) and (lines(i) <>"" or lines(j) <> "") then
           duplicate=duplicate & vbcrlf & lines(i)
           lines(j)=""
           logic=false
          end if
     next j
    ' if no duplicate found then add that line to nonduplicates
    if logic then
    nonduplicate=nonduplicate & vbcrlf & lines(i)
    end if
next i

' then write the duplicate to the duplicate.txt and nonduplicate to nondup.txt or wherever you want