LF398-N: What is advantage of using two of these sample-hold circuits in tandem?

Part Number:LF398-N

Hello,

On page 20 of the datasheet for this part shows an example of typical applications, titled "Fast Acquisition, Low Droop Sample and Hold". The datasheet I'm looking at is:

http://www.ti.com/lit/ds/symlink/lf198-n.pdf

In this example, there are two LF398s in tandem. Could you please explain how this achieves "fast acquisition" and "low droop" compared to doing it with a single LF398?

Thank you,

Jae Jeon