With two documents open in the Revit session, I copy a ceiling from one document to the other.
After the copy, all ceiling types in the target document have two parameters both with the same name "Grid Options"
RVT files at https://drive.google.com/open?id=146fajMwdiR3Vn_JRj_O2iO4USb8VMyqK
It looks like I can add more parameters with the same name.
There are already 2 Grid Options in your empty file, one for ceiling and the other for material.
Maybe you can just delete them before you pasting your ceiling in.
They are actually different Parameter with same names.
They are only the same if they are the same parameter defined in a shared parameter text file.
Hi @harrymattison,
The reply above is correct; this is not a bug. Revit sees parameters as GUIDs, not names, and will duplicate if you copy/paste or transfer project standards parameters with different GUIDs. Please see the article below for steps to remove the duplicates and let me know if you have any questions, thanks!
Duplicate project parameters showing in Revit

Please think about it this way... Does the Revit user ever want to have multiple parameters with the same name? Would this be confusing? Might the user like a warning if this is going to happen?
@harrymattison wrote:Might the user like a warning if this is going to happen?
If there were a warning, users would be asking for a way to turn it off.
Running into this issue still in Revit 22. IT IS A BUG! Revit warns you if you give the same number to two different spaces, even though they are different GUIDs. Why? Because having two spaces with the same number will cause issues in your design and schedules. Guess what? It does that in other things too, such as mechanical equipment where I have 4(!!!) parameters called "Phase" for electrical phase. FIX THIS AUTODESK! Don't tell me it's not a bug here, but you've clearly worked in other parts of the software to avoid it/fix it.
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