Bukkit

What steps will reproduce the problem?
1. Entering Nether or End portal

What is the expected output? What do you see instead?
Enter to the world called "terrain" or in case of End portal, enter to the world called "Hoth"

What version of the product are you using?
Latest, 4.5.1

What version of the craftbukkit/bukkit are you using?
1.4.7-RB 1.0

Do you have an error log of what happened?
No error log, since it is not an error, just a malfunction.

Please provide the result of /mw debug below:

12:24:38 CONSOLE: [INFO] Now printing debug information
12:24:38 : name >-< version >
12:24:38 : Bukkit >-< git-Bukkit-1.4.7-R1.0-b2624jnks (MC: 1.4.7) >
12:24:38 : Multiworld >-< 4.5.1 >
12:24:38 CONSOLE: [INFO] ----------------------------------------------
12:24:38 : configState >-< enabled >-< loaded >-< pluginName >
12:24:38 : False >-< False >-< False >-< WorldSpawnHandler >
12:24:38 : True >-< True >-< True >-< NetherPortalHandler >
12:24:38 : False >-< False >-< False >-< GameModeChancer >
12:24:38 : False >-< False >-< False >-< EnderChestBlokker >
12:24:38 : True >-< True >-< True >-< EndPortalHandler >
12:24:38 : False >-< False >-< False >-< WorldChatSeperatorPlugin >

My config.yml file:

# # options.debug: must the debug output be printed?
# # options.difficulty: what is the server diffecalty?
# # options.locale: what set of lang files must be used, supported: en_US, nl_NL, de_DE, it_IT
# # spawnGroup: used to set whits worlds have whits spawn, difficult to use
options:
  debug: false
  difficulty: 2
  locale: en_US
  usecreativemode: false
  usecreativemodeinv: true
  blockEnderChestInCrea: false
  useEndPortalHandler: true
  useportalhandler: true
  useWorldSpawnHandler: false
  useWorldChatSeperator: false
spawnGroup:
  defaultGroup:
    spawn: Slender
worlds:
  Slender:
    seed: 101
    worldgen: Normal
    options: ''
    difficulty: 2
    autoload: true
    netherportal: terrain
    endportal: hoth
    spawnGroup: defaultGroup
  Slender_the_end:
    seed: 5768111391162896688
    worldgen: The_End
    options: ''
    difficulty: 2
    autoload: true
    spawnGroup: defaultGroup
  TARDIS_WORLD_Xcalibur10:
    seed: 101
    worldgen: Normal
    options: ''
    difficulty: 2
    autoload: true
    netherportal: terrain
    endportal: hoth
    spawnGroup: defaultGroup
  hoth:
    seed: -8942181852053554663
    worldgen: Plugin
    options: HothGenerator
    difficulty: 2
    autoload: true
    netherportal: terrain
    spawnGroup: defaultGroup
  caves:
    seed: 2123
    worldgen: EpicCaves
    options: ''
    difficulty: 2
    autoload: false
    netherportal: Slender
    endportal: Slender
    spawnGroup: defaultGroup
  GallifreyCitadel2:
    seed: 777
    worldgen: Normal
    options: ''
    difficulty: 0
    autoload: true
    netherportal: slender
    endportal: hoth
    spawnGroup: defaultGroup
  terrain:
    seed: 342
    worldgen: Normal
    options: ''
    difficulty: 2
    autoload: true
    netherportal: Slender
    spawnGroup: defaultGroup
  Slender_nether:
    seed: 5768111391162896688
    worldgen: Nether
    options: ''
    difficulty: 2
    autoload: true
    netherportal: terrain
    spawnGroup: defaultGroup

notice it may not work 100% correctly incase of an end portal because of the detection, will try to reproduce this