Chum change

What is the origin of the phrase 'chum change'? Isn't 'chump change' incorrect?

I take it you have looked this up in the archive, but are unsatisfied with what you found. "Chump" is often used to describe a dupe or a naive fool. The Oxford English Dictionary tells us that "chump change" means a small or negligible amount of money, that it's slang of African-American origin, and that it can be found in print at least as early as 1967.
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