Without wanting to offend anybody. Aside from pure collectors why do people own very similar binoculars at the same time in parallel? I understand to own something for high magnification, something light weight and such but like almost the same model in several copies? Wouldn't make sense to me.
Not offended in the slightest! I gladly confess my three 8x30 are nostalgia binoculars, though I do use them regularly (not so much this year, but over the time period I've owned them, yes - quite often at that). They fog up when it's cold, and the coatings don't match even a reasonable made in China product of today (oh god if only...), but neither of those are issues in nice summer weather, and I find great pleasure in using something so light, handy and beautifully made. I have to remove my glasses to use them, and therefore use them only when I won't need to go quickly to or come quickly off my binoculars, but even that has a certain element of charm, as side light is blocked off better than when I have my glasses on - which contributes greatly to the "immersive view".
I like to have the choice between 10x40 and 10x50 - 10x40 smaller, handier, for when I want closer birds to look bigger than in 8x magnification, and 10x50 with its larger exit pupil that is more comfortable when "in the glasses" for most of a three to five hour session, scanning for distant targets. My 10x50 (old Zeiss West) is also somewhat a nostalgia binocular, but it's still pretty good at the task I use it for.