50 on a single race? That shouldn't happen. Should be more like 20ish.
And you shouldn't get any duplicates either with the exception of weapons which have different skin variants.
I have maxed out 1k and 5k boxes (and 12k almost) and you aren't able to buy anymore boxes from that category once you have every item from it.

since we're talking about loot items, what do ded shiny stuff actually do?

Probably intended to be the equivalent of Master Crafted weapons, aka better stats than normal.

Of course, this has yet to be fully implemented yet, though.

What do you mean by t2 weapon mods ? T2 weapon or t2 mod ?

Well better accuracy I think. Well at least slab slugga and shoota got better accuracy and stats shows that. Not sure about chopa, deffgun etc.

I remember a couple of people mentioning they got duplicated on higher priced boxes, someone got 3 chainaxes (same skin, only one available in inventory) and the other got the the mod multiple times but i don't remember which

t2 weapons is power weapons of 10k value(or 400lp base cost) such as the powersword or the plasma cannon/rifle
t3 are 16k cost items like the powerfist and the multimelta.

while the 5k boxes do contain all the mods and melee weapons in that tier (mace/axe/swords with mods) the mods for the ranged weapons such as plasma cannons/lascannons/meltaguns and plasma rifle are not in there with the exception of the plasma rifle grips and a plasma rifle 2x scope.

t1 weapons btw are bolter, knife ,chainswords, narthecium and the heavy bolter.

the 5k crate also contains the mods to create a stalkerbolter and the mastercrafted variants of bolter/hb ...

t2 mods are those used for t2 weapons.

with 1k loot box I got a differently colored deffgun (red).
I got shoota that look colored on the image of the gun in the gun selection but still appear without color on the character.

I got mods for the choppa axe, basically a damage increase OR a penetration increase (didn't get a grip)

I got almost all mods for a shoota (the barrels, the munition, the grip, bought the scope to try it out).

got a different looking base slugga, with some mods

got a different looking knuckle with a damage mod.

I got a different standard choppa (with spikes) and mods for it.

I think that's about all I got and maxed it already.

I didnt get strict duplicate (though the different colored shoota that actually display the same looks like a bug or incomplete feature).

I have...heaps of doubles too

Is there any way to see what's in your inventory as a whole