Sometimes the trigger build step is triggering two builds instead of just one. The step log output is as follows:

16:35:49,030 INFO - Checking step execute condition...
16:35:49,030 INFO - Step execute condition satisfied, executing...
16:35:49,070 INFO - Checking step execute condition...
16:35:49,075 INFO - Step execute condition satisfied, executing...
16:35:49,156 INFO - Executing pre-execute action...
16:35:49,156 INFO - Running step...
16:35:49,213 INFO - Executing pre-execute action...
16:35:49,213 INFO - Running step...
16:36:33,276 INFO - Executing post-execute action...

So here you can see that the executecondition, the pre step action and the execution is done twice. Only the post-execute action is just called once. This lead to 2 builds being requested almost simultaneously which already lead to bad timing issues.

Wait for start and waitfor finished are set to YES in our case.

Do not know if anybody else already experienced such problems.
But at least it would be great to have the step log some more information like
"Requested build of configuration <configpath> (id: <requestid>)"
"Build <version> (id: <buildid>) has started" (in case wait for start is YES)
"Build <version> (id: <buildid>) has finished" (in case wait for finished is YES)

Currently it is pretty hard to find out what's wrong.
Or maybe you have an idea why this could happen?