Collectible Card Game Headquarters

Describe the Bug:
Tokens put onto the battlefield by Feldon of the Third Path's activated ability are sacrificed during the end step of the turn during which Feldon's ability has been activated, even if that ability is activated during an end step.

Which card did behave improperly ?
Feldon of the Third Path

Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
C14U, duel

What exactly should be the correct behavior/interaction ?
Tokens put onto the battlefield by Feldon of the Third Path's activated ability are sacrificed at the beginning of the next end step. This means that if that ability is activated during an end step, the token is sacrificed at the beginning of the next turn's end step.

Are any other cards possibly affected by this bug ?
Mimic Vat
Probably other cards that use the same wording.

Odd question for the devs, but how is the end step implemented in manalink? I ask because under the rules discard happens during cleanup and no actions may be taken then, but in the game there is a discard phase before cleanup where actions may be taken.

We're under the pre-6th edition rules, I don't know precisely how the end step was ruled at that time.
As for the bug, stay tuned.