
I look at the eyes. If it's light blue it's Alyosha, if it's purple it's Jurij
You can also look at the parting Alyosha part his hair on the right side, while Jurij part his hair on the left. Here's a page where they are side by side...but I still prefer the eye method
https://www.mangago.zone/read-manga/the_first_commandment/uu/to_chapter-25/pg-31/
Jujucat I love you so much
Thank you for mass uploading the official chapters