Why routing plan comparison gives 50% assurance for morning run 2

Summary:

I routing run report if we click on comparison and compare 2 reports then in parameter column there is one row for Assurance for morning run 2 it is 50% and for morning run 1 it is 99.900000000000006%

But both routing plans are identical only difference is run on different time
But why it gives 50% assurance for morning run 2

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):