Hi Matadem, there is a RemoveDuplicates command that might help with that:
https://moi3d.com/4.0/docs/moi_command_reference10.htm#removeduplicates

Select all the lines, then press the Tab key and type RemoveDuplicates and then press Enter to run that command.

There isn't anything set up for duplicates to show in a different color. However, when there are duplicates the display will be a little darker in those spots. It's pretty subtle though.

- Michael