It probably doesn't matter but I would spread it out. Salmon is easy to freeze in individual portions, and easy to thaw and cook. So, it wouldn't be too hard to space it out. You could also cook it all at once, but eat the leftovers a couple days later. Leftovers are less boring if spaced out. If they are concerned with you getting too much mercury, then spacing it out would not give you a big dose twice in a row.

Not stupid! I’ve wondered this myself.

It's not meant to be taken so literally. The idea is to get overall balance over the course of a week, month, year, and lifetime. That may mean you eat salmon 2 days in a row and then don't eat it again for a week or two. It might mean you have it Tuesday and Friday like clockwork.

If something is recommended to be eaten twice a week (like salmon), does it matter which two days in the week to eat it? As in, is it better to eat the food Sunday and then midweek or is two consecutive days okay?

I am so sorry if this is beyond stupid.