It is not just the analysis - you get a different observable light pattern. Don’t see how you can say the underlying reality is the same in view of that.
Also, the core premise that detection does not change the underlying reality is absurd. Detection means transfer or exchange of information. Information cannot be transferred or exchanged without a transfer or exchange of energy. (You find a way around that and to heck with the Nobel - let’s talk, implement the process, and become so rich that Bill Gates looks like a pauper in comparison.) And it is axiomatic that a transfer or exchange of energy changes the underlying reality, whatever that may be.
The problem is that spunkets invokes "reality" when it suits his argument, and ignores "reality" when it doesn't. He also tends to make false distinctions between reality on the one hand; and "conceptual" things, such as logic or mathematics on the other. This despite the fact that there is quite obviously a connection between mathematics (say) and "reality" as he would typically invoke it.
It's not that he's dishonest, I just don't think he's careful.
Yes, there's a different pattern and that's indicated by the proper analysis of the underlying reality in the experimental configurations. In the case of the straight double slit, there's a sum of the waveforms from two beams involved, Σψi. In the other case, where one, or both of the beams are examined, each beam is analyzed as simply Ψ, no sum. The interference only comes in, when Ψ is a sum. ie. (Ψ=Σψi).
The reason for that can be seen if one examines the wavefunction Ψ, which is not an observable. It contains an arbitrary phase difference, eiφ, which is irrelevant with respect to the observable. If one does something during the experiment to introduce prior events, or the experiment contains prior events, either of which has the effect of eliminating that arbitrary phase factor, the sum is no longer appropriate. In that case, both beams must be represented by their own wavefunctions. In these cases, the beams are said to be correlated, or entangled.
In the case of the double slit, that prior event was the causal event for the correlation, or entanglement of the a pair(s) in separate beams. The experiment is analyzed as a single slit, because that correlated pair no longer has the arbitrary phase difference that's essential to generate the double slit pattern.
The prior event is a constraint on the system, like Brilloin zones in metals. Electrons in metals are not allowed trajectories which would allow for interference patterns to occur within the metal. In all these various cases, the mystics refer to these situations as spooky action at a distance. No such action at a distance ever occurs. The correlations occured at some earlier time when the particles were in causal contact. Causal contact in the double slit case, is when some prior "observation" event happened.
Here's some remarks on a couple of "spooky" events. In the one case, the experimentors attempted to do amazing nonsensical things in order to analyze particle behavior after they had already annihilated. In the other, particle physicists analyze the particle beam collision data that contains correlated particles. Those particle experiments appear to have spooky action at a distance, because it appears as one particle waiting for the other to decay, before the other knows what it must become. In reality the phases in their decay mechanisms were correlated when they were on prior causal contact.
In short, one must be able to recognize when to use Ψ, or Σψi for the wavefunction. Each of them represent some different underlying reality.
Two electrons with trajectories 180o opposed and on paths separated by 1000 meters open space pass. They deflect. How has the underlying reality of each electron changed? Do you consider all electrons to be different, because they are on different paths?
" And it is axiomatic that a transfer or exchange of energy changes the underlying reality, whatever that may be."
The minimum amount of energy to exchange one bit of info is Emin, where Emin=kTln(2) joules/bit. How has the underlying reality of the universe changed in the case of the 2 passing electrons? Is it significant?