I didn't try this, but when you run regedit.exe to open and edit your registry (if you're not uncomfortable doing that), there should be an entry for version 7.0 under HKEY_LOCAL_MACHINE\SOFTWARE\Cerious Software Inc.
Within that are three fields (keys) that store the name, code and number of users. Maybe you can edit the name there (or delete those keys), then exit regedit, launch TP7 and see if it will let you enter the correct details. I'd make a system checkpoint first so you can restore the system to its current state if things don't work out.