Datastreams can sometimes appear duplicated if mousing over many stations at once

[C-Loftus]

There is a chance that extra datastreams from other stations can unintentionally show up in the UI for a given station.

To reproduce:

• Mouse over a station
• Mouse over to other stations in quick succession
• Mouse over the same original station again quickly

Unclear if this has been fixed in upstream since the test server only has one observation in at the moment. Going to ask maaike to add another few stations.