There are going to be two different wattages for these systems.  You are going to have a lower wattage 750W with part numbers of 5NF18 and 6W2PW which are interchangeable.  The higher wattage PSU will be 1100W with part numbers of YT39Y, GYH9V, 38GYJ which are also interchangeable with eachother. You can not mix wattages so you either need 2 750W PSUs or 2 1100W PSUs. 13th generation Dell PSUs will technically fit but won't work so make sure you are using 12th generation specific PSUs in this system.
Hello, I am trying to check the PSU compatiblity list for PowerEdge R720.    I search the Dell website but I couldn´t find it, do you have any link to check it? List?
Poweredge R720 PSU compatibility list