I have successfully trained both my kitties (Salem Spookypants and Snowy Snugglepants) to walk outside on a leash at the same time!!!! At first I thought this would not be possible...but it is!!!
I trained Salem to walk on a leash when we first adopted him and he has always enjoyed his "walks" tremendously. We adopted Snowy on Valentines day this year at 6 months old, so I quickly got him acclimated to wearing a harness and then walking outside on a leash separate from Salem.
In the beginning it was tough to get them to walk in the same direction....I had both arms extended it opposite directions. But after many trials and errors, they both got the hang of it and now walk together!!!!
We take leisurely walks around my condominium complex, stopping to check out the trees, flowers, and of course the BBQ grills, lolz....
From a outsiders perspective, we must look bizarre! But whatever! I love my two boys, and I know they really enjoy their walks outside on a beautiful day!!!