Double the coincidence, double the low probability
Not only do non-canonical views of Stride being the victim of a different killer require that you accept it was just a coincidental violent homicide that night, but that it is also a coincidence that if you leave the site of Stride's murder at the time Stride died and walk at a normal pace towards Mitre Square you will inevitably meet Eddowes on the same trajectory coming out of the drunk tank. It isn't just a matter of *might* see her, if you go that way, time/speed, you will be in that location, within looking distance of people around you and Eddowes *MUST* be one of them because we know what time she left the drunk tank and which way she headed.
That's two big coincidences you need to accept in believing them unrelated.
The probability is virtually nil of them uncorrelated because of timing and trajectories.
Bona fide canonical and then some.