Yes, the robot pronounces them the same way in the word-by-word mode, obviously , "thinking" that "все" is actually "всё" without the dots on "ё". But in the whole sentence it pronounces all the words correctly.

Unhelpful but possibly intentional - as I understand it, Russians often don't bother adding the ¨ to ë, so when you see 'vsye', it might actually mean 'vsyo'. Duolingo certainly accepts a Roman 'e' when the word to be typed contains a yo.

for me there is a difference in pronunciation in slow version for both words, however, tome the last word seems to sound like znale. Is the last и supposed to sound like э

i listened many times and I do hear the difference

Remember about the case system:

• Все(nom.) всех(acc.) знали.

nein ! was ist das ? Non, qu'est-ce que c'est ?

• Все - everybody, everyone
• Всё - everything

It's clues like that which help listeners "fill in the blanks" - they might not hear things exactly, or the things might not be said clearly, but when you hear a clear 3rd person plural verb, you can retroactively recognize the subject.

1. Знали

2. It doesn't.

Look at the declension table I posted here (above, I think). все is plural. In English, "everyone/everybody" is a collective "plural" treated as a single entity, so it takes 3rd person singular verbs:
"Everyone knows" but "They know"