So I’ve just took ownership of a 84 XT600 43f also bought a Haynes Manuel for it and the air filters are different could well be at sometime in its life someone has changed it, So there is no air box as such but 2 separate round air filters with 2 piece foam on each, and there is a separate small cone shaped metal type filter with a hose going down to the crank case is this normal. 
Scottish Lad 

Parts list diagrams are online as a double-check... 
Sounds like someone replaced the stock airbox with "pod" filters and installed a crankcase vent filter (necessary because crankcase vent probably originally connected to stock airbox, which is now probably buried in a landfill someplace)

As far as a "normal"?  I don't think anyone can answer that?  Since the filter elements are still available from Yamaha, it doesn't seem like a "necessary" modification.
 

Probably just thought it would breath better like that being a twin carbs on a single cylinder. I guess not a bad thing except for inlet noise which some people might think sounds quite grunty & powerful. Just keep the filters lightly oiled if you go near anything like dust. Crankcase breather filter probably gets a breath of oil mist but keep an eye on it I case it's totally dry & could draw dust in as don't think it has a one way valve thingy further down in.