Hi Jose,
Incase SAP's legal compliance are met as well as your company legal compliance are met, there is no issue in having 2 productive instances 1 for each company.
Having 2 productive clients in single instance for 2 different companies will attract maintenance issues
- Patch upgrades
- OS patches
- Database patches
- Cross client object modification ( very critical).
- Backup window
- Downtime window
Hope this helps.
Regards,
Deepak Kori