I am not aware of any difference in the efficacy of name brand or generic forms of Alprazolam. I would not advise doubling your medication doses, without prior consultation with your treating physician.
I had the same problem with the generic brand. It depends on the drug company you get them from. I was using the generic from the company called "purepac" and I did not feel anything from them. However, when I went to a different pharmacy their generic came from the company "Greenstone" and these worked great. Hope this helps.
I take the generic and it works the same as the regular.
I don't know about the generic of xanax because I have never tried it but I tried the generics of both Ativan (Lorazapam) and Klonopin (Clonazapam) for alcohol withdrawal and an anxiety disorder and they both knocked me on my butt. I tried the Ativan first and it was not so strong but the Klonopin made me feel really fatigued and lazy. I have recently gone back to the Ativan and feel much less tired now.