We have the same setup and have found it varies from Mac to Mac even when they are running the same version of OSX in this case 10.3.2
One thing that does seem to help is running Disk Utility "Repair Permissions" and MacJanitor. I've found I can then run two copies of AC 7 for a while.
Other glitch is that one of the two ArchiCADs running will "lose" the dongle but I've not found a way round that one.
Here is a link to my Tips page with a link to MacJanitor and instructions on how to repair permissions
http://homepage.mac.com/fuzzytnth3/fuzzyblogs/tips/C1938766018/E32958628/index.html
AC versions 3.41 to 25 (UKI Full 5005).
Using AC25 5005 UKI FULL
Mac OSX 10.15.7 (19G2021) Mac Pro-2013 32gbRam AMD FirePro D500 3072 MB graphics