会话对每个用户都是唯一的。您只需要在注销时删除/放弃用户会话。你应该在这篇文章中掠夺：如何：使用在ASP.NET 2.0中使用SQL Server进行表单身份验证Microsoft Docs [ ^ ]

Sessions are unique per user. You just need to make that you remove/abandon the user session on logout. You should take a loot at this article: How To: Use Forms Authentication with SQL Server in ASP.NET 2.0 | Microsoft Docs[^]