In the 1950s, a shady outfit called Obetrol Pharmaceuticals made a popular over-the-counter diet pill called Obetrol. If you're familiar with any of: the 1950s, shady pharma, or diet pills, your next question will be "did it contain amphetamines?" and the answer is yes, loads of them. Obetrol was a mix of four different amphetamine salts: racemic amphetamine sulfate, dextroamphetamine sulfate, methamphetamine saccharate, and methamphetamine hydrochloride. Why did they need four different kinds of speed? I'm not sure. The uncharitable explanation is: for the same reason Dr. Nick's Cure-All Home Remedy has twelve different herbs, ie customers think things with more ingredients are better.
By the 1970s, people figured out meth was bad, so Obetrol replaced their two methamphetamine salts with two more kinds of non-methylated amphetamine. But the FDA continued to crack down, and although the historical paper trail goes kind of dark, it looks like Obetrol had disappeared by the 1980s.