Random-ness

For some reason I was thinking about the movie "It's a Wonderful Life" this morning, and the two policemen Bert and Ernie. Which of course, are also two Muppets.

Then I was wondering why Jim Henson picked those two. Did he have a fondness for that movie? Were they just good generic names? Or did Rosencrantz and Guildenstern just not flow as easily off the tongue when thinking of background characters?