Understanding Horse Racing 'Couplings' at the Arc de Triomphe

Question
hello,went to the arc de triomphe 2 yrs ago and somebody was on about coupling i have forgotten the meaning of this and wonderedif you could refresh me as i have a friend going this year and i tried to explain to him but he could not understand my explanation please could you send me the answer. i know its something to do with trainers/owners having 2 or more runners in a race many thanks dave

Answer
Rather than me explain it I found this description at: http://www.picksandplays.com


In general, when two or more horses entered in a race belong to the same owner and/or are trained by the same trainer, they are called "coupled" horses. The coupled entry is comprised of two or more horses and are a single betting interest. For example: Mrs. Smith owns horse A and horse B. Mrs. Smith's entry would thus be 1 and 1a. This is considered a bet on #1 for betting purposes. Once in awhile, there will be more than one coupled entry: Mrs. Smith owns Horses A and B while Mr. Jones owns Horses C and D. Mr. Jones' entry would be numbers 2 and 2a.
While this seems complex, what it means is that you get two horses for the price of one. However, it usually means that a horse you thought would be at long odds may be affected by the other "coupled" entry