I was working with the People Editor Control and realized there are a couple weird things you need to do before you can read values into the control and save values into a list. Here is a samples related to saving multiple/single user details into a people or groups column in a list.
SPFieldUserValueCollection UserCollection = new SPFieldUserValueCollection();
string UsersSeperated = pplEditor.CommaSeparatedAccounts.Split(‘,’);
if (UsersSeperated.Length > 0)
foreach (string UserSeperated in UsersSeperated)
SPUser User = web.SiteUsers[UserSeperated];
SPFieldUserValue UserName = new SPFieldUserValue(web, User.ID, User.LoginName);
This way we can store single or multiple user names in a People or Groups column from a people editor group.