Are you sure it is really the same version? There have been a lot of updates lately that don't have any changes in the release notes, so unless you are noting down the build number, it would be easy to think that the same version is appearing. I'd be really interested to see a screen capture showing an "About OmniFocus" window and a upgrade window both showing the same number...
The other possibility that comes to mind is that you've accidentally started up the old version again, in which case seeing it suggest the same upgrade wouldn't be so surprising. Do you have the box for "keep old version" unchecked in the upgrade/install dialog? By default it is on, which isn't really needed at this point in the alpha/beta process, IMO. The builds are quite stable, and Omni gives you access to the old ones if you need them at
http://www.omnigroup.com/application...ad/sneakypeek/