This reminds me of a girl I know who asked if methadone and methamphetamine were the same thing because they both had "meth" in them. I tried to explain what a "methyl" group was and that was the end of that.
Short answer, no, "methyl" isn't an ingredient, its part of the chemical name "methylphenidate". Amphetamine is just that, amphetamine. Methamphetamine is an amphetamine molecule with a methyl group attached to it. These are all related drugs but you can't mix and match parts of their molecules like you can mix and match parts of their chemical names.
However, to answer your question, OP, yes, something would happen, you would be taking methylphenidate and amphetamine at the same time, but you wouldn't be taking methamphetamine.