Ok, heres the revised code. Inside the commented box change "Summary"
to whatever the actual summary sheet name is, change "U" to the letter
of the column that you would like to use to show the number of
instances, and change "2" to the number of the row in which the data
starts in.(i.e. I entered 2 assuming there was one row of headers and
data begins in row 2). Let me know if this works for you or if you
have any questions.

Sub Test()
Dim cell, cell2 As Range
Dim Dupe, Dupe2 As String
Dim LRow, LRow2, i, i2, DRow As Long
Dim n, DCol As String
'===================================
n = "Summary" 'Name Of Summary Sheet
DCol = "U" 'Column to show count
DRow = 2 'Row to begin count
'===================================
Worksheets(n).Activate

LRow = Worksheets(n).Range("A65536").End(xlUp).Row
Worksheets(n).Range(DCol & DRow & ":" & DCol & LRow).ClearContents
For Each cell In Worksheets(n).Range("A" & DRow & ":A" & LRow)
i = cell.Row
Dupe = Worksheets(n).Range("A" & i).Value &
Worksheets(n).Range("B" & i).Value & Worksheets(n).Range("C" &
i).Value _
& Worksheets(n).Range("D" & i).Value & Worksheets(n).Range("E" &
i).Value & Worksheets(n).Range("F" & i).Value _
& Worksheets(n).Range("G" & i).Value & Worksheets(n).Range("H" &
i).Value & Worksheets(n).Range("I" & i).Value _
& Worksheets(n).Range("J" & i).Value & Worksheets(n).Range("K"
& i).Value & Worksheets(n).Range("L" & i).Value _
& Worksheets(n).Range("M" & i).Value & Worksheets(n).Range("N"
& i).Value & Worksheets(n).Range("O" & i).Value _
& Worksheets(n).Range("P" & i).Value &
Worksheets(n).Range("Q" & i).Value & Worksheets(n).Range("R" &
i).Value _
& Worksheets(n).Range("S" & i).Value &
Worksheets(n).Range("T" & i).Value
Dim n2 As Single
For n2 = 1 To Sheets.Count
If Worksheets(n2).Name = Worksheets(n).Name Then GoTo nx
LRow2 = Worksheets(n2).Range("A65536").End(xlUp).Row
For Each cell2 In Worksheets(n2).Range("A1:A" & LRow2)
i2 = cell2.Row
Dupe2 = Worksheets(n2).Range("A" & i2).Value &
Worksheets(n2).Range("B" & i2).Value & Worksheets(n2).Range("C" &
i2).Value _
& Worksheets(n2).Range("D" & i2).Value & Worksheets(n2).Range("E"
& i2).Value & Worksheets(n2).Range("F" & i2).Value _
& Worksheets(n2).Range("G" & i2).Value &
Worksheets(n2).Range("H" & i2).Value & Worksheets(n2).Range("I" &
i2).Value _
& Worksheets(n2).Range("J" & i2).Value &
Worksheets(n2).Range("K" & i2).Value & Worksheets(n2).Range("L" &
i2).Value _
& Worksheets(n2).Range("M" & i2).Value &
Worksheets(n2).Range("N" & i2).Value & Worksheets(n2).Range("O" &
i2).Value _
& Worksheets(n2).Range("P" & i2).Value &
Worksheets(n2).Range("Q" & i2).Value & Worksheets(n2).Range("R" &
i2).Value _
& Worksheets(n2).Range("S" & i2).Value &
Worksheets(n2).Range("T" & i2).Value

If Dupe < "" And Dupe = Dupe2 Then Worksheets(n).Range(DCol &
i).Value = Worksheets(n).Range(DCol & i).Value + 1
Next cell2
nx:
Next n2
Next cell
End Sub