Signify direction of duplicate values in a column

I have a column of about 9700 values, many of which are duplicates. What I would like to do is be able to look at a cell and determine whether its duplicate value occurs before (lower row number) or after (higher row number) than that one.

My plan was to use a combination of for/next and .findnext, but I've at this point in my two-weeks of vba experience not been able to make .find or .findnext work. Basically my plan was to change the right border of a cell's value for "appears below" and the left border for "appears above." This would avoid the confusion of a cell sharing a top or bottom border with another cell.

Does anybody have any suggestions? It seems like a fun puzzle to work out, but I think I'm out of my depth.

Thanks very much to all of you.

Here's a sample of the data I'm working with (gonna be a long post, hope I'm not violating any rules):

In this data, you can see that the value of cell A6 would be the same as A376. Ideally, this would mean I'd see the right border colored green on A6 and the left border colored green on A376. A1 is, of course, a header.

stockcode
30791014
30664113
8698927
8698933
30682111
30682087
30682101
31253113
8682185
8682093
8622614
8624196
9496979
31217061
8624353
9134945
8698589
30721726
30721725
30721727
8641200
30721712
30721713
30721714
9499024
9499026
9499025
39965829
39965828
39965827
8671059
8673473
39963435
39963437
39963433
8682177
9166732
31414237
9148136
30721974
31263245
8641722
8685516
30664041
30664042
30721383
30721382
30721717
30721716
30721696
30721698
30721715
9192992
30721709
30664340
30664338
39891781
39891793
39998304
39891775
39891787
39998294
39891778
39891790
39998299
39892724
39967700
39967927
39892727
39967698
39967924
39967948
39967699
39967926
39967949
39885111
39885109
39885110
9155288
1343999
30721719
30721721
30721720
8641254
9499310
9204062
8624222
9204061
8641255
9204060
9499904
8637222
30660542
9499153
8637714
8637427
9438235
30739571
9438236
8698154
8637076
30728403
9814069
9192678
8637215
30669774
8691888
8633764
9499034
8637392
30716660
31217622
31217623
31217625
8637393
30715805
8622723
8622724
8622731
8622732
8622721
8622727
8622728
8622725
8622726
8622729
8622730
9499266
9499267
8637408
9499398
9499397
9499636
8651385
8651382
8651379
9499637
8637409
9438241
31267436
30661774
9488735
8674874
30618547
9166346
31359474
31470478
31217667
30863733
9438246
9438247
8624286
30710979
9438248
9438249
8624284
8691912
8698727
9499758
8698074
30669774
8624286
30710979
30795247
8624284
8691912
9499758
8698074
30669774
8624286
30710979
9499164
8624284
8691912
8698727
9499758
8698074
9499478
9438237
9438287
30660792
30744345
30744346
30744347
8622338
8622838
8622839
8698122
8698123
9166697
8622840
8622981
30772053
8671036
30796586
30664195
8622943
8685753
8698060
8698318
8698996
8698997
9190803
9190936
9484507
9484631
8685503
30673258
30673259
1188364
8685839
9499414
9499559
9451649
9481791
31373831
30664327
31202244
274511
8666253
30695184
9451408
274511
8666253
8682133
9499038
274511
8666253
9499020
274511
8666253
8633140
274511
8666253
30660592
9162391
274511
8666253
30748020
8698501
274511
8666253
9451348
274511
8666253
9451347
274511
8666253
9162393
274511
8666253
30748782
8698499
274511
8666253
30695185
8698502
274511
8666253
8622748
274511
8666253
9499019
274511
8666253
9451346
274511
8666253
9451345
274511
8666253
9162395
274511
8666253
30789048
9499551
274511
8666253
8698504
274511
8666253
9162394
9162392
8633138
8698500
9491784
8622862
8698503
8698046
8671048
8671050
8698167
8671047
8671049
8698155
8698157
8671055
8671056
8671057
39985061
39986945
39985049
39985288
8698225
8698857
8637171
9499549
30660838
8698223
9499061
9481247
8682095
8698041
8685885
8685762
9496986
30741604
30741605
30741633
30741597
8698230
8698856
30741600
30741601
30741632
30741096
30741101
30741232
30741233
30741098
30741598
30741599
30741596
30741602
30741603
30741634
8624350
9204956
8622875
8622876
8623108
9452189
30660443
9452189
30660437
30660439
9452189
39966522
39966521
39966520
30730085
39899313
39899316
39899312
39899315
39899311
39899314
9196876
9196141
9197488
9196183
9188998
9438263
39984780
39984779
39984781
39984778
30775885
9452314
39984788
39984787
39984789
39984786
30682110
30682111
8698043
8637076
9814069
9192678
30698360
30660645
30786670
30786671
8637076
30669774
8691888
9814069
9192678
30698360
30786663
30786664
30786665
274511
8666253
30664605
274511
8666253
30664609
30695338

I tried the code above and let it run for a couple minutes but eventually had to break out. Nothing was noticeably different with formatting.

Thanks again, folks.

Yeah, I could definitely see it running faster on 400 rows than on 9700. Maybe I just need to be more patient. Thanks for the help, I really appreciate it