Third leaver function and other questions

This question is for those who use a CAT IT38F. While watching Casper A Spirited Beginning, I noticed in the CAT IT38F, there are 3 joysticks. I can only theorize 2 of them are for the lift arms and bucket cylinders, but there's a third joystick. On newer model CAT IT38s, theres a single joystick that works like up+down for the lift arms and left+right for the bucket cylinders, but theres still that extra joystick beside it. What does that extra joystick do?

Next, why are some bucket cylinders configured like this (well actually, these can have two bucket cylinders like the IT38s) But others like the IT38 series look like this?

PS, ghosts, that's not a bulldozer, bulldozers have crawler treads. You hijacked a front end loader. After watching this, I've all of a sudden taken a bit of an interest to front end loaders with 4-in-1 buckets as if I need to multitask on a medium-sized construction site with many digging and loading tasks, I'll use a backhoe loader, while I'll use an excavator to do some deep digging work, while a front end loader will be used to get huge loads of dirt loaded into trucks without needing a big cleanup bucket of an excavator so that I don't damage the asphalt/concrete road with it's metal tracks.

Well, Iam not the most qualified but I’ll have a stab at it.
Firstly, the IT line of loaders are integrated tool carriers, designed for versatility rather than dedicated production digging or loading.
The third function lever is to control any hydraulic tool that the loader may be carrying, like the 4in1 bucket etc.
The production machines have a Z bar linkage with one large cylinder pushing out to crowd the bucket back.
This arrangement allows for higher breakout forces when digging.
The twin cylinder arrangement of the IT machines allows much better visibility of the tool being carried and a true parallel linkage for precise level lifting.
With later series loaders, Cat have attempted to combine the best of both machines.

Ok thanks for the info. I almost forgot, there are also 3 floor pedals in the IT38F. The one on the far right is the accelerator, the middle one is the brake, but what is that third one on the left? It isn't the auxiliary hydraulics, is it? Like for a breaker/hoe pack?

The left pedal is brakes also, but neutralises the transmission when depressed, and transmission re-engages when released. This is the brake mainly used when working, unless travelling downhill or roading.