An example—in spoken English, certainly—is the recent popularity of the phrase “is is.” A second is is usually (though not always—see the fourth word of this sentence) both redundant and superfluous. I just searched “is is” on National Public Radio’s Web site and was presented with 1,810 hits. Some of the most recent are:

• And the media loves those hundred-million dollar numbers. The reality is is that it’s worth a lot less—35.5 million guaranteed. (Sports correspondent Stefan Fatsis, on “All Things Considered.”)
• But the truth is, is it’s no longer insurance if the government says they’re always going to bail you out. (Rep. Ron Paul, on “Talk of the Nation.”)
• The big difference is, is that right now farmers—and other employees, actually, too—are not required to verify the information. (Milwaukee Journal-Sentinel reporter Georgia Pabst, on “Tell Me More.”)