If you have multilple levels in a multi-story building and you want all the datum elevation tags for each level in a building section to read "T.O. Concrete". How do you accomplish this ?
I guess ultimately - what are you looking for? Every level or reference datum needs to be unique as stated. You can always hide the datum's if you want and just put in some symbols and text. But if something moves - you will have to go back and move everything with it. So you loose some of the base functionality of the software.
Your revit files will not look exactly like AutoCAD - that is not a bad thing - but it is a change which is never easy.
Levels must have unique names, but it is up to the user what to display in the level family . If, due to the kind of work that the user is doing with Revit, he is not interested in showing level names but just in showing a note, such as "T.O.Concrete" in all of them, then, the level family could be modified. The actual name of each level will continue to be "Level 1" , "Level 2", but the level family will show just the value of "Note", (for example), a shared parameter that is included in the family and added to the project. Another option is to leave both labels in the family, "Name" and "Note".
Can you hide the parametric datum elevations and add dummy elevations in each view?
Here's what I was about to post and then I thought maybe you
are not talking about levels but elevations. Interesting anyway.