I have heard this the second time today and I can vouch for the double drop as I have seen that myself.
M+ seems to be Blizzards focus more than raids when it comes to loot acquisition asI its very difficulty to see Blizzard’s team meeting when they come out of it and say yes this is good for raiding …nope nope nope
That fits, as 23 people would result in 4 items with a 60% chance of a 5th.
As for duplicate drops, the logic that determines what items drop is run independently each time, so having multiple of the same item drop isn’t uncommon.
We only got 4 drops off the last boss, with 27 players. 
All other bosses dropped 6 items.
Even 5 is bad for content you can complete only once a week 
Group loot = bad.
Personal loot = good.
Group loot brought back = very bad.
Therefore, I am sad.
I’ll bet at least lfr has personal loot next tier.
When did you kill it? we got 6 from razageth on Wednesday for 27 or 28 (I forget which)
This was rarely brough up in legion/BFA, where the formula would have resulted in 23 being 5 with a 75% chance of a 6th, and there was even less chance of an item being good due to the extra 1-3 layers of RNG.
You still can get loot you don’t need though. If you only run 1 hunter in group, two bow CAN still drop and one is wasted. People act like there’s no wasted loot in group loot and it’s just not true.
This was how the loot was before BFA, and it NEVER worked. It’s not going to work now.
Personal loot has problems, but not like this. Even CASUAL guilds are now forced to do splits, because it’s just so much more efficient. Before no one did splits because it’s not worth the time due to personal loot.
It’s a step back in the wrong direction.