400Q Guide wrong awnser?

Is there anything else “intangible” besides Goodwill & Other Intangibles that could also impact the combined company? 

Yes. You could also have a Purchased In-Process R&D Write-off and a Deferred Revenue Write-off. 

The first refers to any Research & Development projects that were purchased in the acquisition but which have not been completed yet. The logic is that unfinished R&D projects require significant resources to complete, and as such, the “expense” must be recognized as part of the acquisition. 

The second refers to cases where the seller has collected cash for a service but not yet recorded it as revenue, and the buyer must write-down the value of the Deferred Revenue to avoid “double-counting” revenue. 

Now my question: Why should you write down Deferred Revenue? 
Ofc all items need to be valued at fair value in an aquisisiton, but if the deferred revenue is previosly accurately valued, why should there be a write down?
And what is meant by "double-counting"?