Software basics · Beginner

Duplicate vertices

Stacked points that look joined but secretly split a mesh apart

Also called Overlapping vertices, Doubles

What are duplicate vertices?

Duplicate vertices are two or more points in a mesh sitting at the same spot without being joined. The model looks fine, but the surface is split there, which causes shading seams, z-fighting, broken modifiers and failed 3D prints. Merging them back into one point fixes it.

Think of it like this

It is like two pieces of fabric laid edge to edge with no stitching: from across the room it looks like one cloth, but pull it and it comes apart.

Where it fits in a 3D project

  1. Create
  2. Surface
  3. Rig
  4. Animate
  5. Render
  6. Export

Create: Building the shape: modeling, sculpting, scanning or generating it.

How duplicate vertices work

  1. 01Copying, mirroring, joining or importing can leave points stacked on top of each other.
  2. 02Each copy belongs to different faces, so the surface is not connected there.
  3. 03A merge tool finds points closer together than a tiny distance.
  4. 04It welds each group into a single vertex and reconnects the faces.

Where duplicate vertices are used

  • Cleaning up imported, scanned or AI-generated meshes
  • Fixing seams after mirroring or joining parts
  • Preparing watertight models for 3D printing

Beginner tip

Run merge by distance right after joining or mirroring parts, and check how many vertices it reports removed. Keep the distance small so it does not weld details that should stay separate.

Terms related to duplicate vertices

Duplicate vertices FAQ

How do I remove duplicate vertices in Blender?
In edit mode, press A to select everything, then choose Mesh > Clean Up > Merge by Distance, or press M and pick By Distance. Raise the distance in the panel that appears if some remain.
Where is Remove Doubles in Blender?
It was renamed Merge by Distance in Blender 2.90. It is the same tool, found under Mesh > Clean Up or in the M merge menu.
What causes duplicate vertices?
Duplicating parts in place, mirroring without merging the center, joining separate meshes, and some file imports. They are easy to miss because the model looks whole until it is shaded, modified or printed.
What is merge by distance?
A cleanup tool that welds vertices closer together than a set distance into one. It is the standard fix for duplicate vertices and also closes tiny gaps between parts.

Updated October 29, 2026 · Browse all 3D terms