Exactly. I’d be willing to bet that they put the IB on there specifically because the Motrin one they’re imitating has it on there.
Ultimately, the way to check is to look at the active ingredient listing. In your example, it’s 200 mg ibuprofen, which is the same as Advil, and all the other generics. AFAIK, 200 mg is the maximum OTC dosage.
Years ago I was a tech for the old Long’s Drug, working between a half-dozen stores in the Seattle-Tacoma area. None of them shelved the drugs the same way: all alphabetical by generic name at one store; alphabetical by trade name at another. Grouped by classification, or grouped deliberately not by classification so as to prevent grabbing the wrong one.
Apocalypse-wise, your best bet would be to get some brains and barter them with the zombie pharmacist on duty for whatever you need.
So I have an (expired) pharm tech certificate, and took just enough biochem to be dangerous. 
I’m still mostly in the same circumstances as @puzzlegal above - and I still have my Merck’s and CRC (old editions) that I could reference. But even so, and to the quote above, I’m pretty certain I’d fail UNLESS it was an “un-looted” drug store. Especially if it’s a zombie apoc, and I’m trying to get by with whatever minimal light I can get without drawing attention. Just … no.
And that’s assuming none of the labels have faded, gotten wet, and on and on and on.
Granted, there are similar examples that are more plausible, or better explained in different examples of the fiction.
28 Days later, the spread is so fast that there’s certainly a lot less of a run on anyone/anything, and of course, the character is a (nearly completely) trained medical professional.
Or jumping to a different genre, in Firefly, when they go in to loot the hospital, they’ve literally written notes down on what to grab and have the advantage of a well lit, well organized option.
It’s also the same as their regular ibuprofen, which made me extra-confused. Like was there some inactive, unlisted ingredient that affected absorption or whatever? I looked and looked on both packages and on the internet and could not find any clear answer, lol. Turns out, as with most confusing consumer things, the answer was simply marketing. Sigh.
(And that was before I knew “USP” was a mark of purity/performance/etc)
I wouldn’t overcomplicate the search. I’d simply take the 1960s-era pickup truck that’s been modified to run on wood chips or whatever, break into the pharmacy and load as much as I could into the back of the truck. Then I’d head to a surviving used book store and pick up the final (2017) print edition of the Physicians’ Desk Reference. Then I’d head back to the camp and start matching the drugs to their descriptions and throwing out the ones we’d have no use for.
But save any green ones for a really amazing party. 