Wait... Who am I?
ROS: My name is Guildenstern, and this is Rosencrantz.
GUIL confers briefly with him.
(Without embarassment.) I'm sorry--his name's Guildenstern, and I'm
Rosencrantz.
~Rosencrantz & Guildenstern Are Dead by Tom Stoppard, Act I. page 22.
I found it humorous how many were confused as to who was Guildenstern and who was Rosencrantz...including said two characters. I could be wrong, but I think this is in an attempt to make fun of the fact that it is easy to get the two confused in Hamlet. I know I, for one, often confused the two when I was reading it...and that was with the characters' names right there--in all capital letters, mind you. I can imagine how confusing it would be without those labels.
It seemed like the overall tone of this play was to make fun of these two characters, as well as other aspects of Hamlet--possibly even all Shakespeare plays. Towards the end of Act I, there is one stage direction ("POLONIUS asiding unintelligibly until--" Page 52) that I believe makes fun of the many asides in each of the Shakespeare plays.