Steve, as mentioned, yes it is for dual hydraulic controls. The "standard" one which it the implement lift (on a twin stick it is the inside stick, closest to the dash) that raises and lowers the implements. The "optional" one is to control the front hydraulic outlets (on a twin stick, it the outside stick). The only factory implement, that I know of was the hydro angled blade. I have a hydro angle blade also. It is really nice to be able to angle the blade from the seat. I did it the manual way for 40 years. I had the 1450 for nearly 10 before I got the hydro angle blade. I do have a picture of it mounted if you would like to see it.
Also, in the Quietline models:
1x00 model number (800, 1000, 1100, 1200) were the gear drive models. The 1100 was even unique itself....
1x50 model number (1050, 1250, 1450, 1650) were the hydro models. The 1450 and 1650 came standard with hydraulic lift and lights.
A quick rule of thumb on the IH Yellow and White 3 digit cub model numbers. If the model number is an even number, the tractor is a gear drive. (70, 100, 102, 122, 104, 124, 106, 126, 108, 128). If the model number is an odd number, the tractor is a hydro (123, 105, 125, 107, 127, 147, 109, 129, 149, 169).... Some of the 2 digit models dont follow this. The 70, 71, 72, 73 and 86 are all gear drives. On all these models, the first digit(s) are the horsepower..
The 82 series then goes off all on its own..... The 482, 582, and 582 Special are all gear drives and I think have a 16 briggs twin in them. The 682, 782 and 982 are hydros. The 682 and 782 are the "same" tractor with a KT17 Kohler 17hp twin, but the 682 is a manual lift and the 782 is a hydraulic lift. The 982 is a Super Garden tractor, it's a hydro, hydraulic lift with a 19.9hp Onan Twin. The frame is longer and it has larger tires. The 782D is a 3 cylinder Kubota Diesel, hydro, hydraulic lift. The 1282 didn't come along until CCC and it was a 12hp Kohler Single, and manual lift. After the CCC switch to 4 numbers, I lost track.....