Can somebody tell me why their two of them and Why there in here?

As above!

As the title asks, is there a reason to play the original version of ArmA 2 when all of its content is in Operarion Arrowhead? Is this a Left 4 Dead / Left 4 Dead 2 situation where there is still some differences between the two versions and a reason to play L4D instead of the levels in L4D2, or is it just that there isn't really a reason and it is best to just play everything in OA?...

I'm trying to access Controls part of the settings, but the game just crashes to desktop with no error screens. Has anybody faced this issue, what to do with it?

I bought the arma X anniversary edition and all the items show up in my steam library including Arma 2 (as it should) but when going to the Arma 2 store page or any of the bundles including it, the game shows as not owned. Also adding it to my cart still gives me the option to purchase for myself, can anyone help?...