# E4057

Compiler diagnostic name: `constructor_duplicate`.

The constructor is duplicate. Constructors in the same enum must have unique
names so construction and pattern matching can identify one variant
unambiguously.

## Erroneous example

```{literalinclude} /sources/error_codes/4057_error/top.mbt
:language: moonbit
```

## Suggestion

Rename the constructor to a different name.

```{literalinclude} /sources/error_codes/4057_fixed/top.mbt
:language: moonbit
```