If you build a grabber that uses a "Replace" action to substitute substrings in the description field (#DESCRIPTION) the modified value is appended to the original value.

h4. Steps to Reproduce
In a grabber put the following actions:

<Actions>
    <Modify channel="*" field="#TITLE" search=" \? " action="Replace"> - </Modify>
    <Modify channel="*" field="#DESCRIPTION" search=" \? " action="Replace"> - </Modify>
</Actions>

Replace the search expression with something that can be found in the description field.
In the grabbed EPG you can see that the description is duplicated whenever it includes the substring " ? " while for title it works correctly.

h4. Additional Information
The issue was reported here: http://forum.team-mediaportal.com/webepg-136/grabber-modify-field-description-duplicates-description-75454/

The cause is that the replace action uses GetElement/SetElement to get the original value and set the resulting value. But description field is handled differently in SetElement, the new value is appended to instead of replacing the original value.