Hmm, here's an interesting story. It appears that One More Day wasn't the first time Mephisto reared his ugly head in Spider-Man's book. That would be Amazing Spider-Man #274.
This was brought up in a previous thread as an attempt to defend OMD by listing this as an example of when Spider-Man "helped" Mephisto (In OMD, Mephisto unravels Pete and MJ's marriage because their love was pure and destroying it was an affront to and victory over God himself). I decided to give the issue a look to see if Peter's actions were similar to the one he took in OMD.
This took place during Secret Wars II, in which the Beyonder wanted to destroy the entire multiverse
Disclaimer: This was a thirty-page issue with no ads. Thus, I am posting ten pages.
The Beyonder has arrived in Mephisto's lair, with the intention of erasing it from existence. Mephisto attempts to buy himself some time and tries to convince Beyonder to divert his attentions elsewhere.
Beyonder then chooses his champion--Zarathos, the Spirit of Vengeance, who had been imprisoned by Mephisto for centuries.
The Beyonder explains the rules of their bet: "Since Spider-Man is an individual motivated by a deep sense of responsibility, all Zarathos has to do is get him renounce his responsibility in some concrete fashion." If Spider-Man persists, the multiverse's destruction will be postponed for the twenty-four hours. If not, the Beyonder will proceed with his plans.
Spider-Man, unaware that the fate of the entire multiverse is resting on his shoulders, is taking photos for the Daily Bugle of a hot car ring that's being held in a warehouse. He overhears, however, of the gang's plans to have Wilson Fisk, the Kingpin of Crime, assassinated at 6:00 when he attends a dinner reservation.
Zarathos torments Spider-Man with visions of what he considers to be his greatest failures. First up is Norman Osborn as the Green Goblin, who blames Spidey for his death (at this time, Norman was still considered dead) and for failing to save him. Spider-Man knows this can't be Norman, but begins to question his sanity.
Peter runs into his parents, who call him a disappointment for dropping out of college and failing to reach his true potential. Peter wakes up from this nightmare, only to find that his face is covered in boils. Peter gets into a cab to go to a hospital, only to find out that the cab driver is Captain George Stacy, who blames Spider-Man for letting him die. The cab turns into some sort of flying demonic hearse, and Peter finds himself falling.
Peter manages to avoid a blast from a demonic figure whose face is covered by a shroud. He introduces himself as the Ravager of Souls and the Living Spirit of Vengeance.
Zarathos tells Spider-Man that its his sense of responsibility that is torturing him, and all he has to do is to simply give up.
With this, Mephisto has won the bet. The Beyonder agrees to let the multiverse live for one more day. He admits that he has seen much that he must ponder, but that doesn't mean he has changed his mind yet.
So after reading this, would you consider Spider-Man helping Mephisto here to be the same as him making the deal in One More Day?