PuTTY + cluster + server fingerprints

We are using PuTTY for automated SFTP transfers to a cluster consisting
of two servers; the cluster is connected to via an alias hostname.
PuTTY will cache the fingerprint for the server it is directed to and
store it in the Windows Registry associated with that alias hostname.
The administrators of the cluster switch alias redirect between the two
servers once a month to ensure a stable failover environment. The
problem for our automation is that it fails each month because PuTTY
will not store both fingerprints against the same hostname, only one
may be associated with the alias hostname, so each month we have
manually connect and re-accept a fingerprint before we are running
again.
I realize part of SSH security is to uniquely identify a hostname with
a unique signature but is there any workaround for a cluster situation?
Thanks for any input!

Glenn

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