The `Rules.match` function now receives an optional `allow_duplicate_metadata=True` argument, which changes the structure of `Match.meta`. By default `Match.meta` is a dictionary with metadata names and their corresponding values, if a metadata name appears duplicated in a rule, the last value will be used. For example, consider the following rule:

```yara
rule demo {
   meta: 
     foo = "foo #1"
     foo = "foo #2"
     bar = "bar"
   condition:
      false
}
```

In that case `Match.meta` would be `{"foo": "foo #2", "bar": "bar"}` by default (`allow_duplicate_metadata=False`), but with `allow_duplicate_metadata=True` it would be: `{"foo": ["foo #1", "foo #2"], "bar": ["bar"]}`.