ADLink reports that we should not have a <Heartbeat> section in our OpenSplice configuration files when using version 6.11. Apparently that section was causing the repeated historical data (which has been fixed in 6.11.1 but may also be fixed in 6.11.0 by simply removing that <Heartbeat> section).

To quote ADLink's response to # 00020916: Repeated/Missing historical data:

A fix to this issue is available in the 6.11.1 version of OpenSplice that is now available through the customer portal. Please could you update to this version and confirm whether this solves the issue you are facing.

You could also remove the below section from the config file, as it is the section causing the issue:
<Heartbeat>
<Scheduling>
<Class>Default</Class>
<Priority>0</Priority>
</Scheduling>
<StackSize>6000000</StackSize>
</Heartbeat>
Since periodic heartbeats are no longer sent in OpenSplice, this section is no longer required.