3D model
The same shape under two names.
Two parts in your design are geometrically equal, but have a different name or a different part number. Usually it is the same part that was created twice, and that means buying twice and managing twice.
Published 21 September 2026
01 What it is
Same shape, different name, briefly explained.
Parts with the same geometry are parts whose shape and dimensions match while the name differs. Sometimes rightly so, for example a left and right version that happen to be equal; often not.
It is a silent error: the model is right, the drawing is right, and yet you have two part numbers for the same thing.
How you notice it
- Two part numbers with the same description
- Two parts with the same dimensions and the same material
- A copy of a part whose name was changed and the shape was not
- Purchasing orders the same thing twice from the same supplier
In a check
This shows up as comment in the check of the 3D model. You judge what has to be done about it.
02 Example
What it looks like.
Example design GRP-2210 (demo)
- Part A
- BRK-114 bracket
- Part B
- BRK-118 bracket
- Geometry
- equal
- Consequence
- two part numbers, two purchase orders
BRK-118 was once made as a variant with an extra hole, but that hole never came in. The two numbers both continue to exist and are both managed.
How it comes about
- Saving as a copy to make a variant, after which the change was never made
- Two engineers who draw the same part independently of each other
- A part from an old project that was taken up under a new number
- A standard part that was also modelled as a custom part
03 Approach
Find, fix, prevent.
How to find it
You find this by comparing the shape instead of the name: putting parts with equal dimensions and equal geometry together, even if they have different names.
- 1 Open the STEP in the free check.
- 2 Go through the lines about the same shape under different names.
- 3 See whether it is a legitimate variant or a duplicate creation.
- 4 Check what is in your PDM system under both numbers.
Fix
- Choose one part number and replace the other in the design.
- Set the old number to obsolete in your PDM system, with a reference to the number that stays.
- Update the BOM and the drawing, including the position numbers.
Prevent
- Search the existing parts first before you create a new number.
- Use standard parts from one library instead of modelling them yourself.
- Check new designs for equal geometry before release.
With BOMproof
Every release, without having to think about it.
BOMproof puts your STEP model, your PDF drawings and your Excel BOM side by side and points out every deviation: with a pin in the 3D model and a balloon on the drawing. You tick off what is correct.
04 Frequently asked questions
Same shape, different name.
01 Is this always wrong?
No. Mirrored parts that happen to be equal, or a part that deliberately exists under a customer number and a number of its own, are legitimate. That is why it is reported as a comment, not as an error.
02 How is it established that the shape is equal?
By comparing the geometry of the parts, not the name or the description. Parts that have the same shape and dimensions come back as a group.
03 What does it cost if you leave it?
Twice the stock, managing two drawings and carrying through a revision twice. And with a change, the risk that only one of the two is adjusted.
05 Often seen together
Other errors from the same corner.
You never want to hunt for this error by hand again.
Upload your model, your drawings and your BOM and let BOMproof check them against each other. Book a demo with your own design.