From the readme.
To install DEVONthink or DEVONnote, simply drag the application file from the mounted disk
image to your Applications folder.
How do I replace the expired Beta (DTPO2) with this new one? I get this error when trying to overwrite:
I have the same problem.
As I was getting duplicates of the Sorter, I decided to download a new copy and start over again fresh. But now I am getting these same messages.
(Somewhere in the past I did see what to do about this, but now cannot find it.)
Update. I rebooted the system and it let me install it.
Update 2. I mean I could launch it from the .dmg, but when I dragged it to the Applications folder, I got the same errors.
Weird. I can launch it from the downloads folder, but when I launch it from the Applications folder, I get this message. Something got messed up, and I was surprised to see I couldn’t use it (expired) since I’ve used it recently and it didn’t try to update from within the app.
Last post on the matter. I couldn’t even eject the .dmg and have a freeware program called What’s Keeping Me,
lifehacker.com/398613/whats-keep … your-files for when a disk won’t eject. The thing that was running was Sorter. I killed that process and was able to install to the Applications folder, and it now launches from within the Applications folder.
Note that, from public beta 3 forward, updates can be a lot less work than downloading the update from the DEVONtechnologies Download page, unzipping the file, opening the .dmg file as a disk image, and dragging the application to the Applications folder. (If Sorter is running, it can be killed in Activity Monitor.)
In Preferences > Update, check the option to check daily for an update when online.
If an update is found, you will be notified and given the opportunity to request that it be installed. If you confirm, the application will be automatically downloaded and installed for you.
Thanks, Bill.
I’m now clear on difference between upgrading and downloading. Also, I had forgotten (and could not find) about using Activity Monitor to quit the Sorter.
Please update the readme in the .dmg to take into account the Sorter issue.
My updates are set for daily.
Thanks 
The Sorter will automatically be restarted as of public beta 4 when a new version is found, downloaded and installed through the update feature.