Hi @leathej1,
K6 VUs are sequentially numbered. The VUs execution the default/exec function start at 1 and go up and the VU(s) executing the initial init context and setup/teardown is numbered 0.
Due to scenarios VUs in a given scenario (if there are multiple) may not be ordered but in the whole instance if you see VU number 200 there are another 199 that are also there.
Can you provide any code sample that reproduces the behavior that you are seeing?
Here is a post explaining how to get unique indexes.
Hope this helps you!