# XO0423: a format's wire string given twice

A field may override its shared wire name (`as "name"`) once per format, with `json "..."`, `sql "..."`, or `xml "..."`. Two strings for the same format leave its name ambiguous. Keep one. See core 2.2 and decision 0315.

## Example

```xo
struct User {
  id json "id" json "ID": Int
} derive Json
```

## Fix

```xo
struct User {
  id json "ID": Int
} derive Json
```

Run `xo explain XO0423` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).