JOSM: Merging Duplicate Natural Nodes

I’ve been working with vector files (canvec) lately and have been getting a lot of duplicate node warnings.

In the original vector file if a lake is surrounded by a wooded area, they share their boundary nodes. But when copying shapes to a new data layer each shape has its own copy of those nodes in the exact same position. In an area with spotty terrain this can add up to a few thousand duplicate nodes per NTS grid. Is there a tool in JOSM to quickly merge these nodes back together? I’d rather not add hundreds of thousands of unnecessary extra nodes to the database (it also makes my uploads take longer).

One thing I experimented with to good success is uploading straight from the vector file after using filters to carefully select and remove any object that are already on the server (highways, waterways, water, places, amenities,…). Perhaps 25-50% less nodes to upload depending on overlap between different types of objects, particularly when winding rivers are involved.

Besides the information in the OSM wiki about the CanVec data:

Have you already had a look at the archive of import mailing list? See

Maybe there are some hints about a better dealing with that data … or ask there directly, maybe someone has already an idea abouit your questions.