Why can I not wonder trade the same species of pokemon out but I
can receive multiples of a species on the same day?
This is VERY tedious and a rather annoying oversight and I would
suggest to change it but the current state of that forum as well as
the website not receiving any major updates in the last few years
make me feel like suggestions are pointless and won't be added
regardless of how much quality of life they'd bring to Pokeheroes.
I think the reason is to avoid wonder trade to get saturated of the
same specie (even so, it already happened), i really dont see a
purpose to the diferent specie rule...
Yes that is pretty much the reason for that. It's to avoid for
people to spamming worthless Pokemon like Magikarp and hoping they
get something valuable for it.
Also, you can receive 2 or more of the same species, because your
Wondertrades happen with different users. Like your Pokemon A gets
traded with User A, and Pokemon B gets traded with User B. So it
can happen that both users put up the same Pokemon