Prevent me from creating events that duplicate existing cases

[ChrisStrykesAgain]

I was writing a module that interfaces with hardware and created an "initialize" request event to call the driver's init. Had I been thinking I would have realized there is already an "initialize" case native to DQMH, but the tool went ahead and scripted it out. The only indication of a problem was a broken run arrow due to duplicated case names.

[Olivier-JOURDAN]

It will slow down events creation time.