Workflow activity error on voting


I'm getting this error during a task completition

I find in logs the AML that caused error:

<Item type="Activity" action="EvaluateActivity">
<Path id="1A9BF5EE8BAB4D5885D0680C931ADB81"><![CDATA[Review]]></Path>
<Task id="44FD3E46B1DC4F21B3CCBD517B266970" completed="1">
<Task id="C6B7EC937DD6470B9D910BDA68D8AE12" completed="1">
<Authentication mode="">

I try also to apply this AML using nash but error is the same "An item with the same key has already been added" how I can complete the WF activity?