Can I display dual subtitles simultaneously (original language and my native language) with different colors and custom positioning for language learning purposes?
Welcome!
That’s solely up to the players. There are no features for that at the Matroska container level.
GOM Player+ is what I use for this purpose, although I’m not sure about having different colors. I have one subtitle at the top and one at the bottom as my setup for this.
There is a free version of GOM Player but it’s not good.