SEPM Upgrade

Hi guys , I have two SEPMS 12.1.5 in Active/Passive with SQL. I intend to upgrade them to 12.1.6 MP4. Prior to running the wizard for upgrade am I supposed to manually stop the SEPM service on both SEPMs and then run the Upgrade or no need to stop service just run the upgrade?

I.e on SEPM1 stop service , Upgrade . Once completed go on SEPM2 stop service , Upgrade and thats it?

I read somewhere that we have to manually stop SEPM service on both SEPMs prior to performing the upgrade or else it will correct the DB.

Can you guys suggest?

Thanks