Issue with Process Builder:
If a duplicate document and email are getting generated, it is probably happening because Process Builder is configured incorrectly and it invokes same action two times (recursion).

Support Reply:
-You can check setup of Process Builder by viewing this article. If you are using Process Builder with email functionality, you need to modify the Process Builder per this article.

If you need more assistance with troubleshooting what issue is with Process Builder, you can purchase some premium support assistance at $125/hour.