Informal English: kiddo, or kiddie?

Self-tutoring about Canadian and American English: the tutor mentions a possible difference.

Merriam-Webster mentions “kiddo” as a child or kid; on the other hand, Oxford Canadian mentions “kiddie”.

I recall, as a child, reading the word “kiddo” in American books, but seldom hear of it now. “Kiddie” does seem, to me, to be more common (but I’m Canadian).

Could “kiddo” be American for “kiddie?”

Source:

Barber, Katherine et al. Oxford Canadian Dictionary of Current English. Don Mills: Oxford University Press, 2005.

Mish, Frederick C (Editor). Merriam-Webster Dictionary. Springfield: Merriam-Webster, 2005.