VBA Highlight Duplicates if exact text found

[decadence]

Hi I am trying to highlight duplicate cells if the cell contains the same text as another, I have tried using conditional formatting but that doesn't seem to work. The Criteria I need is if text is found either on it's own, between a comma or between a space
Is this Possible?

Example:

[TABLE="class: grid, width: 250"]
<tbody>[TR]
[TD]R1,R3,R3.1,R8[/TD]
[/TR]
[TR]
[TD]R100, R111[/TD]
[/TR]
[TR]
[TD]R2 R3_1 R5[/TD]
[/TR]
[TR]
[TD]R3.1 R9[/TD]
[/TR]
[TR]
[TD]R2[/TD]
[/TR]
[TR]
[TD]R3_1 R50
[/TD]
[/TR]
</tbody>[/TABLE]