Rushi is correct in that hash algorthms can differ on each side - asymetrical traffic passing is supported. What you don't typically want is any session to have packets go across different physical links, as then out of order packets could occur, and not worth the recovery.
There is no standard I am aware of for "LAG" hashing. It is vendor choice of how they do it. In some newer Juniper products and/or new SW, configuration options for the hash method have been added. You need to look at both specific product and SW docmumentation.