I have two. I used to have three but at some point I lost on and couldn't be bothered to go through LL to get it back. My original account from 2002 actually has a significant negative L$ balance on it from having been in a land group. I don't use it anyway so I don't care.
I have 11. I had a club for 6 years in SL and I needed to advertise the club. I closed the club down not due to lack of biz, constantly was busy. But, I was preparing for my multiple back surgeries (which the surgeries are still going on). Right now I'm updating them to mesh since I'm starting to use them when I don't want people to know I'm online lol. Only my closest friends know who my alts are lol.
One premium main, one slightly older life account, one using my real life name, one using the business name, and one named Taber Resident because the group land is in Taber. That’s five altogether because Patsy Stone was lost in the Great Wipe. She was a riot. Stories for another thread.
I have forrestchild which is my main adult account my alt miakistheusagi, which is my child account and premium account. I do have a third alt, but I just use her mainly for helping with testing pose anims.