Schooling kerri tetras with blue/ black emperor tetras?

I'm planning in getting some kerri tetras (Inpaichthys kerri?) tomorrow after much deliberation and I wanted to keep a shoal of them.
That look like this (from google):



But I've noticed my chain fish store has interchangeably used the name 'blue black emperor tetra' with the kerris. The 'blue black' ones seem to have all black bodies and a blue eye in the shops.
They look like thisagain from google):




So I'm wondering, is this because they are the same species, just different colour variety?
Or are they just mislabelled? Looking on the Internet again I can see the name 'nematobrycon Palmeri' also being used?

My main question really is can I buy a couple of black ones to shoal with the main kerri tetra shoal I'm getting?

 

If they are the same species they will school. Colour dosen't matter.

 

If they are the same species they will school. Colour dosen't matter.

Thank you. Next step is to figure out if they are the same species I guess!

 

They are not the same species. The Black is a color form of the standard Emperor Tetra, Nematobrycon palmeri, which is a non-schooling species with territorial males. Inpaichthys kerri, which I prefer to use either King Tetra or Purple Neon, is a schooler like many average Tetras. Rather than the male holding a territory, a male and female will split off from the school to lay eggs quickly. Emperors guard a territory over a breeding area and attract females from the shoals as they swim by. Emperors also get significantly larger than the Kings.

 

They are not the same species. The Black is a color form of the standard Emperor Tetra, Nematobrycon palmeri, which is a non-schooling species with territorial males. Inpaichthys kerri, which I prefer to use either King Tetra or Purple Neon, is a schooler like many average Tetras. Rather than the male holding a territory, a male and female will split off from the school to lay eggs quickly. Emperors guard a territory over a breeding area and attract females from the shoals as they swim by. Emperors also get significantly larger than the Kings.

Thank you! I actually ended up spending a good part of the evening trying to be able to spot the difference, it seems the black emperors don't have the adipose fin like the kerris.
So based on what you've said I will stick to a good group of kerris!