Depending on which font you use, you *could* use a Zero Width Space...

There are games you can play to cheat Revit, but chances are its going to come back and bite you eventually.
Whatever you do, it is "cheating".
This is one of those times when you should be asking yourself "Why do we need duplicate numbers?"
Either the project should be split into two, or you should use unique Sheet numbers - for example, prefix the number with a code:
e.g. 1.A100 and 2.A100

Since you mention shell and interior, I'm guessing these are two Bid Packs for the same building?
And if that's the case, how are you going to identify when "Sheet A.100" was issued? Which A.100?
What if the shell needs a PR after the Interior has been issued? Which A.100 gets re-issued/

You can set two sheet numbers to be the same with Dynamo..... but then your project browser goes blank until you can find and rename the sheet.

In the long run its easier to abide by Revit's restriction here. We do early release packages a lot, and we have two types of sheets that appear in both packages - ones that are identical, and ones which have different information for each package. For cover sheets, which have different information, we use G-001 for the consolidated set cover sheet, and then G-001A, G-001B, etc for each package.

For sheets that are identical on every set we just have one sheet, and use another parameter to indicate which set(s) it should appear in for the drawing index.

We've successfully used "blank" Alt Key Codes to duplicate sheet numbers in models which have multiple bid packages. Arial font has several including alt+0129, alt+0143, alt+0144, alt+0157. I would prefer a unique prefix in lieu of the alt codes but they work when needed.

Some of the architects at my work keep asking for this, but seeing as im the document controller it ain't gonna happen.

I wish we could find a way not to have duplicate sheet numbers but in a lot of our projects there's just no way around it. DOB has a fixed numbering system we have to follow and we split up the project in different filing sets because of timeline constraints. So that means that we'll have A-100, G-000 multiple times.

In the past we tried to create an empty project and link the main project in for each filing set. However, you cannot life reference all the views (no linking to drafting views or legends for example), so it's a big job to keep these different filing sets coordinated.

There are two ideas on Revit ideas that would allow us to solve the issues we're having right now:

- Shared parameters in elevation/section/callout heads (this would allow us to create a custom "numbering" parameter, so could be compromise between the people who'd love duplicate numbers and the people who'd hate them)
- Allow dupicate sheet numbers

I'm posting this here so people who come across this topic after googling (like I did this week) can add their support to the ideas they find appropriate.