Any Davis station that uses the traditional console/logger approach as receiver/logger for data handling is stuck with using the legacy or v1 API (ie the one described in the Davis Serial Tech Ref document) . This has only a single slot for wind data (ie accommodates just a single anemometer) and there's no way of changing this.
The introduction of WLL, which in theory allows an anemometer on all 8 of the wireless channels, changed all of this, but uses a completely different and far more flexible v2 API.
Most of the familiar third-party software (Weatherlink for Windows/Mac, Weather Display, Cumulus/MX etc etc) will have been designed around using the legacy API and so its whole data handling and dashboard only accommodates a single anemometer. None of the well-known software (other than weatherlink.com of course) has caught up fully with the v2 API yet and, to be fair, it would be a huge task to provide full compatibility with the v2 API, eg allowing for multiple anemometers rather than just a single unit, and which is indeed all that most users will have. The one I'm not sure about is weewx, but I suspect that will have similar constraints.
The only solution I can think of right now for more than one anemometer is to use WLL and weatherlink.com on a Pro plan. This provides a multi-anemometer dashboard and then a data store also. If you want to do more with the data then you can download it into supplementary software like the Prowlar program that we run for detailed reporting.