> Both programs want to ensure you only run one copy of themselves. So they create a global mutex using the GUID of their .NET assembly, right?

> So what happens is that both of them are creating a global mutex to ensure only one copy runs, but instead of basing the GUID on their own code, they're both using the GUID of a part of .NET itself. > And they're using the same one!

> Back in 2009, the user "Nathan" asked how to get the GUID of the running assembly. Twelve minutes later, "Cerebrus" answered. And that answer was wrong.

> A year and a month later, it was pointed out (by "Yoopergeek") that it gives the wrong GUID.

> Three years later, Cerebrus returns and fixes the answer. They can't delete it, because it was accepted

> That flawed stackoverflow post is here: https://stackoverflow.com/questions/502303/how-do-i-programm...

Someone at Docker and someone at Razer both copy-pasted the same faulty code from Stack Overflow for preventing multiple instances of their program running at once. Unfortunately the code took the assembly identifier and called GetType() on it which returns the same value for all programs.

The Stack Overflow answer was later fixed but since the programmers no doubt both felt they'd "solved" the problem, they didn't see the fixed answer.