This is typical/common behavior under Mac OS: If the same application is installed and the program/application name ends with a number, then the operating system asks, if the old version should be overwritten or the program name increased by 1. This leads to the increase of the last found program name (e.g. ARES Commander 2019  to ARES Commander 2020,  to ARES Commander 2021, etc.), if the previous install version is not overwritten.