OneDrive creates a file with the computer name appended whenever a conflict is detected. For instance, if you have a file named "MyFile.txt", OneDrive will create "MyFile-ComputerName.txt" in a conflict situation.
A conflict exists when the file has been updated in more than one place. An easy example is with a computer that's not connected to the internet. If you update "MyFile.txt" on the laptop, the file won't sync right away (because there's no network connection). If you also update "MyFile.txt" on your desktop, when the computer connects to the internet, you'll have a conflict, because the file was updated in two places. As a result, OneDrive creates the conflict copy.
You'll have to manually delete the duplicate files. You can easily remove them by using File Explorer and searching for files that have the computer name in them, for example open File Explorer and navigate to the OneDrive folder on your computer, then search in the top-right for the computer name. All files that have that in the file name will appear and you can delete them easier.
The digest email is a summary of new messages posted by members in your network. You can choose to receive this email Daily, Weekly, or Never by changing the option selected in your account's notification settings.
To get to your account's notification settings, log into your yammer account and under the icon with three dots in the top navigation bar, click Edit Profile. Then select "Notifications" from the left-hand column. Under the "Send me a digest of message activity" section header is the drop down for digest sending options. When you're done, click Save at the bottom to put all the changes that you've made into effect.