double-clicking on a file opens it twice
But only for some extensions. files opened with file-roller and shotwell are opened twice when accidentally double-clicked. pdf and txt open once.
I suspect this happen depending on the application design. Some obscure application not specifically designed for elementary may open twice accidentally, wich can lead to problems if the application or the file is heavy.
In order to prevent this, there should be a delay before a second click is taken in consideration.