in salat taraweeh/fajr can you read in 1 rakah warsh and 2nd rakah hafs?.

Question
salaam

in salat taraweeh/fajr can you read in 1 rakah warsh and 2nd rakah hafs?.

i read that hafs has 50+ secondary turuq, does this mean that hafs taught his students 50+ turuqs and how did imam asim teach quran to hafs. did he tell him about all the turuqs, it sounds confusing?

Answer
Wa alaikum assalaam wa rahmatullahi wa barakaatuh,
Yes, in any salah you can pray one rakah in one way of reading and the next rakah in an other way.

Yes, Hafs 'an 'Aasim has over 50 turuq, but that doesn't mean that all of his students learned all 50+ plus ways.  Some most definitely did, or we wouldn't have them today, but it is not a requisite that you have to learn everything your sheikh has learned.  Some only ask for one way from their sheikh.  These different turuq have minor differences are all transmitted in authentic chains from the Prophet, peace and blessings of Allah upon him to the sahabah, to the taabi'een, to those after until  those who read them this very day. 
So, these turuq would not have reached us if they had not be transmitted from the Prophet, peace and blessings of Allah upon him, down through the chain to 'Aasim then to Hafs, then on through the qurra' in solid chains until we have them today. 
insha' Allah it isn't confusing.  Plesae see the following links for more information:
http://www.abouttajweed.com/kb/entry/304/
http://www.abouttajweed.com/kb/entry/502/
http://www.abouttajweed.com/kb/entry/322/