Is there any chance your switching between repos? i mean activating and deactivating extra-devel repository?

The most commen reason i found for the app manager trying to update to a version you allready have, is caused by a dependency that app has wich is not up to date with the version in the repo.

It will look like its updating the app, while infact its one of dependencies being updated.

Anyways im no expert. Im sure others have more insight.