Possible Clues:

• When doubled, a 1965 Dixie Cups song
• When doubled, classic New Orleans song
• When doubled, amply covered New Orleans classic
• When doubled, a classic Mardi Gras tune
• When repeated, classic New Orleans refrain
• Repeated, a famous Mardi Gras song
• When repeated, a '65 Dixie Cups hit
• When doubled, a hit song of 1965 and 1989
• When repeated, an old New Orleans tune
• Doubled, a Dixie Cups oldie about New Orleans