To add to this, there's potentially a similar security problem if you have a bunch of systems with different certificates sharing the same TLS session caching backend or session ticket keys. It doesn't allow any one system to impersonate another, but they can perform active and passive network (MITM) attacks.

For server-side caching, some systems now take into account SNI hostname and use it to prevent contamination. If you're in this situation, it's worth looking into how exactly your backend works.