Hmmm, I just tried the Samsarin PHP Widget for the first time and although the plugin page says that you can have up to 25 instances of the widget, I found that no matter how many I chose, only one was displayed on the Widgets page in admin, and when I used that one there were no more.
Oddly enough on the plugin's settings page where you can delete the contents of any one or all widgets, the correct number of widgets showed up. They are not available on the Widgets page though, so something is wrong. Anyone have experience with this? I know it's a longshot.