MultiWin

From WDSoftware:

MultiWin provides a convenient way to multiboot between different versions of Windows 95/98. If you want to use multiple versions of Windows in one system, like when you want to use Windows 98 and Windows 95 so you could get used to that new Windows 98 first before uninstalling existing Windows 95 from your system, this is the perfect program for you! In fact, there is a bit of incompatibility in Windows 98, so if you upgrade immediately from Windows 95, you might find some program not working properly. For software developers wanting to test their program in different localized versions of Windows like Korean or Japanese without deleting existing version of Windows from their system, this program is a must!