Do you have a link to a double blind study where this was tested?

I don’t.

My cardiologist pulled out a sheet with instructions on how to complain to the FDA, so I’m pretty sure it was common for that drug.

I have personally noticed large differences in side-effects between various generic brands of SSRIs. That's anecdotal, but now I always pick the same generic brand out of the ~5 I have tried for the same compound.

Same here. I always believed that generics were identical until one time the pharmacy gave me a generic for an SSRI. I was suddenly enveloped in physical pain in my chest and neck, so I called my doctor. She told me it happens, generics can cause different side effects and reactions, so she gave me a new prescription specifying the brand and the pain went away...until much later when there was a shortage of the brand name and I had no choice to go to the generic. And the pain came right back.

I believe there's probably some differences - especially in packaging. Some medications are different between generics or between generics and name brand in bioavailability. The title of the article isn't backed up by the content though in this case.

Why do you change manufacturers? I always get the same generic when I get my hypertension pills.

The fact that this is even a consideration is scary, and frankly, what the book was apparently about. I always believed generics were identical.

What I’ve heard anecdotally: The “generic” part of a generic drug is the active ingredient - that should be essentially the same between manufacturers. What differs, however, is the delivery mechanism. So for something that is extended release, the mechanism for releasing over time can vary between manufacturer.

I’m not entirely sure that this is the full story though, I haven’t researched the problem enough.

The pharmacy will change drug distributors, which will change the manufacturer supplying their inventory.

I don’t. I get a different manufacturer every few months.