The COROS POD 2 provides multiple advanced metrics to help you better understand your form and performance. While they are explained in further details in this article, you will find below an overview of the displayed metrics based on the POD 2 location.

*Dual: Indicates that data inputs are coming from both your watch and the POD 2 to create a stable and highly accurate measurement
Why Should You Wear the POD 2 on Your Waist?
Waist-related metrics displayed from the POD 2 refer mostly to biomechanical variables that can help you optimize your running economy/efficiency. Therefore, wearing the POD 2 on the waist would best suit road or track runners looking to improve their running form with the most accurate biomechanic metrics available. A waist-worn POD 2 could then become a reliable tool for athletes throughout their training to improve running efficiency during the off-season or during specific form focused workouts.

Why Should You Wear the POD 2 on Your Foot?
As seen from the chart above, foot-related metrics displayed from the POD 2 refer mostly to distance and pace measurements along with external variables such as temperature and altitude. Therefore, wearing the POD 2 on the foot would best suit runners who wish to gain access to accurately enhanced measurements as well as instant adjustments of crucial metrics such as running pace. For example, short and fast high-intensity interval workouts would benefit from the POD 2 data enhancement.

POD 2 Placement From a Coaching Perspective
The POD 2 placement should be guided by where you’re at in your training journey as an athlete. If you’re a runner looking to improve biomechanic components such as building form and running efficiency, wearing the POD 2 on the waist would provide better insights. If you are a runner looking to improve physiological components such as aerobic and anaerobic metabolisms, then wearing the POD 2 on the shoe would be suggested to benefit from enhanced metrics like instant pace.
Coaches can also benefit from various POD 2 placement metrics for their athletes from both exercise-prescription and analysis standpoints. While foot-worn POD 2 provides performance oriented metrics useful during race day or key workouts, waist-worn POD 2 provides relevant insights regarding running form and injury prevention for coaches and athletes to monitor.

I think there is a confusion on this matter.
O. Coros FAQ It is actually stated that it is possible to connect both pod 1 and 2.
https://support.coros.com/hc/en-us/articles/10351744085012-COROS-POD-2-FAQ-s
Can you please confirm which statement is true?
No, only 1 unit can be worn at a time to ensure proper data collection
Hi, can I use Pod 1 on the waist and 2 on the foot?