RG6 cable question

Hi all.

In planning the structured wiring for my home I thought I'd run two Cat6 cables and one RG6 cable to each bedroom. I have come across some suggestions on the internet that it's better to have two RG6 cables running to each bedroom but I can't understand why. Is this common practice? If so, what would a second RG6 cable be used for other than TV or SKY?

Thanks