Describe the bug

Under conditions I haven't been able to isolate (yet), a Warning can be inserted into the WarningSet more than one time with the duplicates distinguished by different UUIDs. The are both saved when the design is failed, but then when the file is read only one of the Warnings ends up in the WarningSet, and there is an exception (Message with id ... not found) trying to load the second.

Looking for the issue now...

To Reproduce

1. Open the first attached .ork file "late-separation.ork"
2. Run the fourth simulation, "Ballistic". The simulated rocket comes in ballistic, and then deploys recovery devices and has a stage separation on the ground. Save the .ork.
3. Open the saved .ork file. Exception occurs.
   ...

Screenshots / .ork file

.ork file mentioned in report above:
late-separation.zip

For completeness, .ork file that will get exception while loading
late-separation-save.zip

OpenRocket version

Current unstable

What platform are you running on?

Linux

Additional context

As you can tell by the four sims included in the .ork, I've been looking at OR's behavior simulating on mis-configured rockets. I've only seen this turn up on a badly misconfigured rocket.