An inflight store add that is a duplicate may get suppressed by the index or may get added as a duplicate if the original has already been dispatched and acked.
If the cursor traps the duplicate message, it won't get dispatched so it needs to get removed from the store.
Otherwise it will remain till restart and possibly get redispatched and/or hold up gc.
The store removal is only occurring for the jdbc store (that has no separate index to track duplicates). This needs fixing.