That amount could easily be prescribed by a doctor to someone who's a virgin to both drugs. My doctor prescribed me that amount of gabapentin when I had just quit benzos (with a seizure the day I went from 0,1mg of clonazepam to zero)
All that said, they're not a good combo, at least to be. All you're doing is synergically augmeting sedation, you can do that with a benadryl. Any of them or both can be used to mellow down another drug, an upper, weed, opies, that's what I would do if I wasn't trying to quit. And I saw you asking about dosages, gabapentin is 1/6 as potent as pregabalin since pregabalin threads are much more common. Take care, even gapapentoids can lead the wrong path if you're an addict, happened to me, huge relapse started by pregabalin, it doesn't even require a prescription and I was doing coke and oxy a week later. So again, take care and be safe.