LeChuck. In episode 4, LeChuck's original voice actor Earl Boen returns as Demon LeChuck, while his new voice actor, Kevin Blackton, plays LeChuck in human form. It's a full-circle effect, sort of like what happened with Elaine: Demon LeChuck in episode 1 was originally played by actor Adam Harrington (who was replaced in later episodes), but Telltale rerecorded LeChuck's episode 1 dialogue with Boen for the DVD release.
Also, the voices for the Spoon Isle Trio (Pirates Bill, Ted, and Kevin) in Chapter 2 seem to have been rearranged in Chapter 5 somehow. For example, Pirate Bill (Swordfighter) seems a bit tough and rough-voiced in Chapter 2, while in Chapter 5 he sounds like a moderately low-pitched guy with pirate-speak. Also, Pirate Ted (Treasure Hunter) sounds like a bit of a Trenchfoot sound-alike in Chapter 2, but he now sounds like an Irish-accented dude in Chapter 5; and Pirate Kevin's (Thief) like a very tough dude with a British accent in Chapter 2, while in Chapter 5 he speaks like a redneck in a low-voicedSouthern drawl. Different voice actors, perhaps?
And Joaquin D'Oro is voiced by David Boyll in Chapter 1, but in Chapter 4, he has a different voice actor: Andrew Chaikin (a.k.a. Kid Beyond).
The Other Marty: LeChuck. Adam Harrington played his undead form in episode 1 of Tales, then Earl Boen (who had already been brought back for episodes 4 and 5) re-recorded over Harrington's lines in the DVD release of the game.
Talking to Himself: There are a few actors who have voiced so many characters throughout the game.
Straight examples by those actually talking to themselves:
Dominic Armato does both Guybrush (all five chapters) and the Pyrite Parrot of Petaluma (Chapters 1, 2, 4 and 5)
Kid Beyond (Andrew Chaikin) does Coronado De Cava (Chapter 3) and Bugeye (Chapters 3 and 5; as well as Joaquin D'Oro (Chapter 4), Murkel Trenchfoot (Chapters 2 and 4), McGillicutty (Chapter 2) and two of his crew members of the Spoon Isle Trio)
Brian Sommer does Killick Hardtack (Chapters 2 and 4) and Judge Grindstump (Chapters 4 and 5; as well as Marshall (Chapter 1), Rockrib (Chapters 1, 4 and 5), one unnamed Club 41 member (Chapter 1), and two members of McGillicutty's crew).
Aversions by the only actors who voiced different characters who never talk to each other are:
Adam Harrington, who does LeChuck (PC download version of Chapter 1) and Moose (Chapter 3)
Tim Talbot, who does Davey Nipperkin (Chapter 1) and Gaffer Crimpdigit (Chapters 1 and 4)
Roger Jackson, who does Winslow (Chapters 1, 2, 3 and 5), the Club 41 bartender prior to Grindstump (Chapter 1), Hemlock McGee (Chapters 1 and 4), and Galeb (Chapter 5)
Alison Ewing, who does Bosun Krebbs (Chapters 1 and 4) and the Voodoo Lady (all five chapters)
Jared Emerson-Johnson, who does the Marquis De Singe (Chapters 1-4) and one member of McGillicutty's Spoon Isle Trio.
At one time there was going to be an extended backstory on Fisheyes Alabaster in Chapter 3—his life as a pirate, what happened to his eyesight, his later life afterward—according to the interview by Sean Vanaman, but Joe Pinney and the folks at Telltale Games didn't want to make it a bit gruesome, so they shortened out the backstory due to time constraints.
Before that, in Chapter 1, there was going to be a puzzle that would take place in Club 41 entirely in the dark for both the PC and Wiiware versions; but unfortunately, the latter version could only hold 40 megabytes, which the game already was (no wonder the place was called "Club 41" after the 41st megabyte).
According to Telltale Games' Mark Darin, the Spoon Isle Trio from Chapter 2 were nondescript pirates who weren't intended to return in Chapter 5, but he needed more characters in the Crossroads "than our modeling budget allowed", so the trio was brought back, albeit with different voices than in Chapter 2.