I was wondering about running multiple instances of VMware Workstation and Player at the same time (I do it quote often since I need to monitor several VMs at once). I noticed that sometime the file inventory.vmls gets corrupted and my assumption is that it happens because multiple instances of VMware Workstation are trying to update it at the same time. I can rebuilt the corrupted inventory.vmls without info. loss (wrote a small python script) but it would be interesting to know if it is possible to avoid corruption in the first place.
Nope, while running multiple VMware Workstation / Player instances work fine it wasn't really designed to keep the .vmls file from ending up getting corrupt.
This is probably one of those areas where we have to count our blessings (the running multiple instances working OK part) and take the inconveniences on top. It is an issue that can only be resolved by VMware. Nothing you can do to prevent it apart from not editing the VM list when there's multiple instances open.