Building redundancy by creating multiple nfs mounts to a single location

I have been managing a small local Linux cluster for my lab, consisting about two dozens of Ubuntu Linux servers - half of those are headless servers (rack/tower), and the other half are used as desktops by my students. I have setup an LDAP server for centralized account management and setup nfs/autofs mounts for shared file systems - including everyone's home directory. This setup has been running well over the last 8 years and I have been growing my servers over the time. A few times of a year, I found that when the nfs server exporting the home directory or the LDAP server went offline for various reasons, the entire cluster hanged. I am trying to build some redundancy to the system so that when this happens, I have a fallback plan. In a recent test, I noticed that my autofs configured autofs-ldap auto.direct mount to /homes directory, exported from server B, and the /etc/fstab configured nfs mount to /homes dir, exported from server A, can both be mounted, when typing df, this is what I saw

serverA:/local_mount/fstab/mount/export  ... 50% /homes
serverB:/local_mount/auto/direct/export  ... 50% /homes

serverA is configured in /etc/fstab, while serverB is configured in my LDAP system with auto.direct, both pointing to /homes. I found that when the system reboot, /etc/fstab first mount serverA to /homes, then, when autofs service starts, serverB's mount became active and shadows the fstab mount. My question is 1. does this configuration have any risk to use such folder with double-mounts? 2. does this configuration offers any redundancy to my /home dir mounts? for example, if serverB is down, but serverA is up, or vice versa, will my users still have a usable home dir without hanging?