A redundant acronym (ac-re-DUND-uh-nim). Typically an acronym followed by one or more words that are already represented by one or more letters in the acronym.

I created this word sometime in the mid-1990's.
Here are a few acredundanyms:

ATM Machine (Automatic Teller Machine Machine)
PIN Number (Personal Identification Number Number)
My favorite:
ABS Brake System (Antilock Brake System Brake System)
by The Perl Guy October 10, 2009
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