libserdes not registering schema to schema registry when the schema is used for multiple topics

Looking to use the same schema as key for 2 Kafka topics, topicA and topicB. I'm using libserdes C++ client library to produce the records with Schema Registry setup.

When I produce for topicA for the first time, I observe that 2 new subjects are registered on Schema Registry as being topicA-key and topicB-value.

Using the same schema as key, after publishing an event onto topicB, topicB-key subject is nowhere to be found on Schema Registry, only topicB-value subject.

After some debug log printing, I see that libserdes checks in its local cache on the MD5 of a schema. If it is found in local cache, it will return the schema immediately and not register it with Schema Registry.