Several contributions generated after paypal payment
This may not be specific to PayPal - I think it may be related to a bug that has been resolved in the latest release candidate:

http://dist.civicrm.org/by-date/2016-06-26/4.7.9-rc/

Should not be long before it's out.

Here's the JIRA issue on that:
https://issues.civicrm.org/jira/plugins/servlet/mobile#issue/CRM-18661