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<p>No, it won’t hurt the OP’s son. I know one MIT undergrad in the mid-2000s who was a repeat Putnam fellow (the major college math competition) had taken 4 years of classes at U. of Wisconsin-Madison. Just don’t enroll in a degree program.</p>
<p>Don’t hold him back for this or whatever reason you may think of that colleges may not like it, even if it were true.</p>