The 1993 works/factory 888 race bikes used the same exhaust as your 1994 corsa. I tried to get new mufflers for my 1993 bike and Ducati sent me mufflers that were too short. The mufflers on your bike and mine have an extra piece welded into them to lengthen them.
When I found that the 1994 mufflers were different, I was able to get a right side muffler, and instead of having the extra piece welded in, it was now made up using one longer pipe.
""""The 1993 works/factory 888 race bikes used the same exhaust as your 1994 corsa. """" ---> It looks like quite similar but aren't, because of the different diameters tubes !!!
According to your explanations about the lenght of the tubes, let me precise :
If you check the Racing pics 93 and 94, you can see on each pic, the original 93 and 94 exhaust pipes !!! In 1993, Ducati was on trouble with aerodynamic matters for the 888. They decided to make few modifications essentialy about fairings, windshield and pipes ... When I compare my both bikes, I can tell you that the difference is very important and even a first and fast general look on the bike makes immediatly your view different ... The consequences of this improvments are immediately visible at the cans level indeed. Have a look to the following pic and observe the difference between brackets shapes which support the can ends ...