No, you can't have two versions of IE running on the same machine - at least, not officially:
Running multiple versions of Windows Internet Explorer, or portions of Windows Internet Explorer, on a single instance of Windows is an unlicensed and unsupported solution.
There are some third-party workarounds, but these are strongly discouraged by Microsoft.
You can't uninstall a given version of IE, but you can revert any updates that you have performed. For example, if you upgraded from IE 8 to IE 8, you can revert to 8. You do that from Control Panel / Programs and Features / View installed updates.
But the best solution is (as Jeff suggested) is to use a virtual machine. In fact, installing a VM is one of the most useful things you can do on a development system.
Regarding your original question, I haven't seen the behaviour you described. Obviously, you will have to reproduce the problem before you can try to solve it.