Thanks for checking! I looked at the details of the entries, and it looks like it is due to the rounding in the tracker and the way the mileage tracker calculates versus the way the cardio tracker does The one entry is listed as "5mph (12 minute miles)" and the other is listed as 8 minutes per kilometer. 8 minutes per kilometer is actually 12.874752 minutes per mile, so the entries aren't exactly equal.
Remember that these listings are estimates and actual calorie burn will vary from individual to individual. For the most accurate estimate of your calorie burn, you may want to invest in a heart rate monitor.