How come Hispanics don't have longer names, since they traditionally add their Mom's maiden name to their Dad's name? Details?

Or do they "exchange" one of the names?
Update: Or do they "exchange" one of the names? Jose mom's maiden name would be Gonzalez-Morales, and his Dad's name would be Torres-Rodriguez . Would Jose take all 4 names, or would he just be Morales-Rodriguez?
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