remove duplicate value within a row but keep first found value and remove the rest

Are you still using Excel 2010?

With 365 you can use:

Formula:

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For Excel 2016:

=IFERROR(INDEX(2:2,AGGREGATE(15,6,COLUMN($B2:$Q2)/(($B2:$Q2<>"")*(COUNTIF($A7:A7,$B2:$Q2)=0)),1)),"")

copied across and down.

Another option
Assuming your source sheet is Sheet1, the result will be in Sheet2.

PHP Code: 

Option Explicit
Sub dup()
Dim lr&, i&, j&, k&, rng, dic As Object, sp, s, res(), c As Boolean
With Sheets("Sheet1")
    lr = .Cells(Rows.Count, "A").End(xlUp).Row ' last used row of col A
    rng = .Range("A2:M" & lr).Value ' expand range into actual range
    ReDim res(1 To UBound(rng), 1 To UBound(rng, 2))
End With
For i = 1 To UBound(rng)
    Set dic = CreateObject("Scripting.Dictionary")
    k = 0
    For j = 1 To UBound(rng, 2)
        If Not IsEmpty(rng(i, j)) Then
            c = False: sp = Split(rng(i, j), ",")
            For Each s In sp
                If Not dic.exists(s) Then
                    dic.Add s, ""
                    c = True
                End If
            Next
            If c Then k = k + 1: res(i, k) = rng(i, j)
        End If
    Next
Next
Sheets("sheet2").Activate
Range("A2:XX100000").ClearContents
Range("A2").Resize(UBound(res), UBound(res, 2)).Value = res
End Sub 


You're welcome. Thanks for the rep.