I'm actually confused as to how you did this. Buying DLC via fate usually costs thousands upon thousands of fate points, which normally takes months to earn. And there's no situation where the fate cost becomes zero if you own it---it's simply disabled in the fate purchase screen.

Normally, the first step in diagnosing a DLC problem is to check that the DLC is installed: right-click 40K: Inquisitor in Steam, select Properties, then the DLC tab. There should be a list of your owned DLC. Make sure the 'Installed' box is checked on all of them.

But in your case, if what you say is accurate, you've effectively bought things twice. You may want to send an email to [email protected] with your account name and a longer and clearer description of your situation.