Excel has this built-in: highlight range > Home > Conditional Formatting > Highlight Cell Rules > Duplicate values. You can then choose your formatting.
If you want to write a macro to do it, start macro recording, then do the steps above on a sample range, then stop recording. Now you have a sample of how it is done for writing your macro...
I've downloaded your sheet and have a solution using a single conditional formatting formula and a new "key" column in your raw data, no macro is required:
1. New key column (note: you may need to apply fixed formatting like below):
This is copied and pasted into every row so the key looks like this:
2. Conditional formatting formula:
=ISNA(MATCH(RIGHT("00000000"&$A8, 8) & "-" & RIGHT("0000" & H8, 4), 'ShpMarkLog(test)'!$P$9:$P$340, 0)) = FALSE
What this does, is takes the 'Tally-Sheet' Order No. (Col A) and the Ctn cells (cols H to AK) and corrects the formatting to look the same as the key column (P) in the 'ShpMarkLog(test)' sheet. it then does a match check on the range of keys and identifies matches. Then, for every match, the Conditional formatting will color a cell.
* excel001.png - Google Drive
* excel002.png - Google Drive
* excel003.png - Google Drive