Version#reify return new object instance with dup: true options

If we want to compare two arbitrary versions, we can use version#reify to retrieve the model from the version, and then creating a diff between the models  (with activerecord-diff for example)

```ruby
widget = Widget.find(1)
reified_widget1 = widget.versions[0].reify
reified_widget2 = widget.versions[3].reify
changes = reified_widget1.diff(reified_widget2)
```
This strategy fail because reify will not create a new instance. `reified_widget1` and `reified_widget2` are the same object. for this purpose it is possible to call reify with `:dup true` to return a new instance