只有相同的升级代码是不够的.您还必须检查这两个软件包是否具有相同的安装类型，即它们都是按用户或按机器安装的.如果安装类型不同，Windows Installer 将跳过旧版本的删除.

Having the same upgradecode is not enough. You must also check that the two packages have the same install type, i.e. they both get installed per-user or per-machine. If the install type is different Windows Installer will skip the removal of the old version.