The later P.O.V. Sequel of Hamlet, Rosencrantz and Guildenstern Are Dead, subverts Those Two Guys. Rosencrantz and Guildenstern were inspired by Vladimir and Estragon (Waiting for Godot) and went on to inspire Jay and Silent Bob (The Askewniverse films) and even more recently and obviously, Rosenberg and Goldstein of the Harold and Kumar films and Timon and Pumbaa of The Lion King, who then get their own Rosencrantz and Guildenstern Are Dead in the form of the Direct-to-VideoThe Lion King 1 1/2.
Salarino and Solanio from The Merchant of Venice are similar, only with even less relevance to the plot. They also have so little individual personality that some actors refer to them as "the Salads".
Most productions of Macbeth often turn Ross and Lennox (or Lennox and Angus, if Ross retains his considerably large role) into this, often merging said characters with the minor lords like Caithness, Menteith, and the unnamed lord (from III.vi) in the process.
Sir Toby Belch and Sir Andrew Augueface, the two bumbling drunks from Twelfth Night, are the epitome of this trope.