Why do I have 2 Game instances?

I have set up a custom GameInstance class and set this class as my default Game Instance but 2 seem to exist as the Tick function gets hit twice.

The first time the tick is hit with the name as Default_MyGameInstance and the second time around with just MyGameInstance, Unreal seems to create the Default_ class when I start up the editor then the second class when I start the game but then 2 exist while the game is running?

Any suggestions on how to prevent the Default_ class being created as having 2 is causing a few problems.