Describe the bug

When multiple m.reaction events are sent from a user with the same key and rel_type from the same user, it causes their reactions to add up rather than just being displayed once. Multiple reactions can be caused by buggy clients, multiple clients reacting at the same time, or lag.

Reproduction

1. Send a message
2. Get the event id
3. Use element devtools to send this event multiple times of type m.reaction:

"m.relates_to": {
  "event_id": "${event_id}",
  "key": "👍",
  "rel_type": "m.annotation"
}

4. See issue

Expected behavior

Only one reaction of a certain emoji should be displayed for a single user.

Multiple identical annotations (i.e., with the same event type and annotation key) from the same user (i.e., events with the same sender) should be treated as a single annotation.

https://spec.matrix.org/v1.10/client-server-api/#annotations-client-behaviour

Platform and versions

- Alpine Linux edge
- Cinny destkop 2.3.1
- Conduit 0.7.0 alpha ([91764745](https://gitlab.com/famedly/conduit/-/commit/9176474513481a035c63c85b7dc6c0025b950dcf) - 2024-03-23)

Additional context

No response