I was wondering if anyone could help. I have a tab file in MapInfo consisting of just polylines. Each is meant to have its own reference number, however some are duplicated (e.g two lines occupying the same position with the same ID's) I can identify these with a query, but what I need to know is if it's possible to delete duplicates and leave one remaining (it doesn't matter which one as they are identical).

Thanks, Alan

(ps. I also have access to QGIS if it is easier in that)

3 Answers 3


Plugin mmqgis for QGIS. http://michaelminn.com/linux/mmqgis/ (http://plugins.qgis.org/plugins/tags/mmqgis/)- Delete Duplicate Geometries


Have a look at the Delete Duplicates tool that you can find in the Tool Manager. It will let you delete duplicates in a table based on attribute values, such as an ID.

Might be a good idea to create a backup of your table before using the tool.

This is in MapInfo Professional :-)


  • With this tool, you can select several fields to check for duplicates at the same time (e.g., all the fields except the ID. Like this it checks whether there are duplicate rows). Very handy.
    – Motti
    Dec 1, 2023 at 8:49

In QGIS you could try GRASS v.clean (rmdupl), it's included in the Sextante toolkit. See this link.


  • + v.clean(break) in case that lines are overlapping but not completely. Dec 5, 2016 at 8:35

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