If I remember correctly, the filter on the left in your image is an Oil Bath type and the other (just above the carb) is a normal paper element type.
The oil bath air filter is also called a pre-filter, it's purpose is to do most of the initial air filtering and the final filtering is then carried out by the paper element - this means the paper element can last longer before needing replacement as the oil bath filter can be cleaned out and fresh oil added up to the level mark.
I've seen these dual air filters on some Fiats that were destined for very dusty climates/countries - in such countries, a paper element filter on it's own would very quickly become clogged and would need frequent replacement. I once saw an X1-9 sold here in Ireland that had the dual air filters fitted, the build code indicated it had been built for a 'Dusty Region', in this case it was built for Australia
These dual air filters i.e. oil bath pre-filter followed by a paper filter element, are very common on construction, mining and agricultural equipment which are often used in off-road and very dusty environments.
Back in olden times, normal cars didn't have paper element air filters, they either had no air filter or just an oil bath filter.
