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# [Vyxal](https://github.com/Vyxal/Vyxal/tree/version-2), 65 [bits<sup>v2](https://github.com/Vyxal/Vyncode/blob/main/README.md)</sup>, 8.125 bytes 

```
ǎ'øṘøṘ≠;Þg
```

[Try it Online!](https://vyxal.pythonanywhere.com/?v=2&c=1#WyI9IiwiIiwix44nw7jhuZjDuOG5mOKJoDvDnmciLCIiLCJDQ0NDSU0iXQ==)

Bitstring:

```
11010101110010011010011100100011010110100000100001101110100000000
```

I'm fairly certain this is correct.

## Explained

```
ǎ'øṘøṘ≠;Þg­⁡​‎‎⁡⁠⁡‏‏​⁡⁠⁡‌⁢​‎‎⁡⁠⁢‏⁠‎⁡⁠⁢⁤‏‏​⁡⁠⁡‌⁣​‎‎⁡⁠⁣‏⁠‎⁡⁠⁤‏⁠‎⁡⁠⁢⁡‏⁠‎⁡⁠⁢⁢‏⁠‎⁡⁠⁢⁣‏‏​⁡⁠⁡‌⁤​‎‎⁡⁠⁣⁡‏⁠‎⁡⁠⁣⁢‏‏​⁡⁠⁡‌­
ǎ           # ‎⁡Push all substrings of the input
 '     ;    # ‎⁢and filter by:
  øṘøṘ≠     # ‎⁣  Converting from roman numerals to base 10 and then back is NOT the same
        Þg  # ‎⁤Get the shortest such substring.
💎
```
Created with the help of [Luminespire](https://vyxal.github.io/Luminespire).