What version of avast are you using Home or Pro ?
What is your OS ?
The Home version has 7 providers and normally there will only be 6 running (unless you have MS Outlook, not express installed). There should be no duplicates in the providers list, so if you have duplicates then there is something wrong with your installation.
It would probably be best to do a clean reinstall.
Download the latest version of avast
http://www.avast.com/eng/download-avast-home.html and save it to your HDD, somewhere you can find it again. Use that when you reinstall.
Download the avast! Uninstall Utility,
find it here and save it to your HDD.
1. Now uninstall (using add remove programs, if you can't do that start from the next step), reboot.
2. run the avast! Uninstall Utility, reboot.
If step 1 failed it may be necessary to run this from safe mode, once complete reboot into normal mode.
3. install the latest version, reboot.