This is probably correct You have a T8-8 which is a 2mm pitch 4 start lead screw.
This is different from a T8-2 which is a 2mm pitch single start lead screw.

The difference is the if you rotate both a single turn the T8-8 will rise 8mm and the T8-2 will rise 2mm.

IMG_2142.jpg
The Left lead screw is a T8-8 turned one complete revolution or 8mm rise
The Right lead screw is a T8-2 turned one complete revolution or 2mm rise.

You will also note the trapezoidal threads are at a different pitch on each.