Wearing two watches at the same time for ECG monitoring

I am currently wearing two Apple Watches (Series 6 and Series 8) to monitor for ECG due to recent diagnosis of AFib. One watch (Series 8) was issued to me as part of a study for persons with AFib and the other is my personal Apple Watch that originally notified me, unexpectedly, that I was in AFib (I am asymptomatic and only know I am in AFib when the watch alerts me). I was wearing both watches to confirm my Series 6 was accurate in detection of AFib. Now it looks like I can only have one watch monitor for AFib at a time. My Series 8 is collecting data for the study and I was hoping my Series 6 could also be alert me when in AFib. Apparently my study watch let me know I was in AFib yesterday, but uses different software so I did not get the usual vibration of the watch saying I was in AFib. I was hoping my series 6 would let me know via the vibration and notice. It did not go off at anytime during the day. Does anyone know if both watches can be used for AFib at the same time and the data be collected via my iPhone for the series 6?