In a large model, at the moment when I checked, there were more than 5000 Revit warnings. I started resolving the warnings and noticed that a good portion of those warnings are due to duplicate Mark values.
So, in order to avoid a situation where multiple elements have the same value for Mark, I set a rule: we need to recognize the element category, then take the capital letters of the category name. We will keep the existing Mark value and, if needed, add a suffix like _1, _2, etc.
So, for example, in one warning where multiple elements had the value 860, it is now, let’s say, DD_860_1 and DD_860_2. This way, we avoid issues with the Mark values.
Before using this script, please back up the existing project model.
Also, if you wish to download this (and all other scripts) along with my sample files, please visit the Shop page.
The script does not use Dynamo packages.