Combination of Click image block followed by a Drag mouse block may perform a double click as after Click image Drag mouse will also click on block and try perform dragging afterwards this combination sometime results in double click instead of dragging.
Please note that the required delay depends on your double click speed in the computer settings. To check these settings, please go to > Mouse & touchpad in System settings of your computer > Additional Mouse Options > Buttons. There you can adjust the speed of a double click.
If you want the delay in the test case to be the shortest choose the fastest speed in the mouse settings.
For any clarification, please contact our Priority Support.