Highlighting duplicates based on data within the same column - excel

Question

I'm trying to create a macro that searches the B column to find duplicates of the same string, and then highlights said duplicates from columns A to I
I've managed to create something that highlights the correct cells but does not seem to be able to find the duplicates. Not entirely sure where I've gone wrong but I think it could be because I'm adapting a former macro that looked across two sheets
Code:
Sub Duplicate()
Dim rng1 As Range, rng2 As Range, rng3 As Range, i As Long, j As Long
Dim w1 As Worksheet
Set w1 = Worksheets("Sheet1")
For i = 1 To w1.Range("B" & Rows.Count).End(xlUp).Row
Set rng1 = w1.Range("B" & i)
For j = 1 To w1.Range("B" & Rows.Count).End(xlUp).Row
Set rng2 = w1.Range("B" & j)
Set rng3 = w1.Range(Cells(ActiveCell.Row, 1), Cells(ActiveCell.Row, 9))
If StrComp(Trim(rng1.Text), Trim(rng2.Text), vbTextCompare) = 0 Then
rng3.Interior.Color = RGB(168, 188, 255)
End If
Set rng2 = Nothing
Next j
Set rng1 = Nothing
Next i
End Sub

Answer 1

At the moment I see one problem, you are referring to Activecell, However you never activate or select any cell nor range. This makes the color change on a cell that you have selected when running the macro and no other. If you replace activecell.row with variable i the macro should be working fine.

Answer 2

Does this have to be within VBA? The conditional formatting feature in Excel can do this without having to rely on a macro. This should also refresh faster than running the VBA. For this you have to rely on relative references within the conditional formatting, which are relative to the activecell at the time you set up the rule.
Select your data from A:I
Conditional formatting> new rule
Select 'use a formula to determine which cells to format'
Use the formula =COUNTIF($B$1:$B$6,$B1)>1, replacing the first variable with your entire range in column B. The single dollar sign on reference $B1 is very important as it tells it to check column B regardless of which column the formatting is being applied to.

Answer 3

You are always setting rng3 to the same cells, because you never change the active cell. Also, you don't really need to have an extra range because you are already looping through the cells.
Sub Duplicate()
Dim rng1 As Range, rng2 As Range, rng3 As Range, i As Long, j As Long
Dim w1 As Worksheet
Set w1 = Worksheets("Sheet1")
For i = 1 To w1.Range("B" & Rows.Count).End(xlUp).Row
Set rng1 = w1.Range("B" & i)
For j = 1 To w1.Range("B" & Rows.Count).End(xlUp).Row
If j <> i Then
Set rng2 = w1.Range("B" & j)
If StrComp(Trim(rng1.Text), Trim(rng2.Text), vbTextCompare) = 0 Then
rng1.Interior.Color = RGB(168, 188, 255)
rng2.Interior.Color = RGB(168, 188, 255)
End If
Set rng2 = Nothing
End If
Next j
Set rng1 = Nothing
Next i
End Sub