As I know you can achieve the requirement
Install 2nd AOS(with different instance name) normally how you have installed first one .
Now you having 2 database, 2 AOS and once application.
Now if you want work two AOS ‘s create two AOS configurations(in Server config) one for each AOS
Select Database1, AOS1 and application in configuration(in Server config) which you have created for AOS1 and click on apply button on AOS config. Now try to open the AX instance it will work.
Suppose if you want to work with second AOS. Stop first AOS and select second configuration and select Datase 2 and AOS 2 and same application. Click on apply button on AOS config. Now try to open the AX instance it will work.
I hope it helps you to full fill your requirement.
Note: - Check in license for AOS’s. If you have license for only one AOS instance. it will not possible to install more than one AOS instance.