Hey there

Yes you can prepare for class 11 and 12 PCB together. But for that you need to prepare under proper guidance which in the lockdown is difficult but if you are preparing for neet then you can prepare from our e-learning platform. Since neet has almost same syllabus as of board so you'll get benefited in your boards too.

Check the link

https://www.google.com/url?sa=t&source=web&rct=j&url=https://learn.careers360.com/knockoutfull-neet-may/&ved=2ahUKEwjwmKnji6vpAhUfyDgGHU8ACvMQFjABegQIBRAB&usg=AOvVaw34pQhyIev0EhF3q9UoBb7v&cshid=1589176430103

Good luck