When using reports that are based off Campaign Members, the options you select for Sorting records can have an impact on what is brought into your call list, especially if there are multiple contacts in the report with multiple campaign members.

When duplicate persons are found with multiple campaign members, the application will always select the campaign member with the lowest dial count. It does this to attempt to ensure every campaign member, regardless of sorting is called. 

Real Life Example:

Let's say you are importing a Campaign Member report where a Lead has been called a total of 8 times. One campaign was called a single time, while the other campaign had 7 dials against it.

As long as those two records are within the first 2000 records selected to import, it will always select Webinar Campaign 1 (with the lower campaign dial count). In this case, the Sorting will have no impact on what is pulled in, and what is displayed in your session screen. This record will also be updated upon the call being placed.

We can see this on the Import Screen, the total calls is shown as "1":