User blog comment:Ethra/Question from a new-ish player/@comment-37004715-20181229185959

1.Dupes are easier to spark,but i don't like to putting too much dupes in the same team since the same buffs dont stack.But aside from sparking reason and them being avaliable on multiple teams.Dupes also enable you to build them for different situations without the need to reset sp,take kranus for example he has two different paths for sp build.Dupes are also key to getting ragnarok edict,by leveling up unwanted dupes you can trade them for even more merit points.

2.Since bf is all about the powercreep,newer units are almost always better than older units,in terms of buff/stats/sp.The current bunch are mostly 60 cost units.On extremely rare occasions,they will buff/rework a old unitFor reference you can go to reddit,theres an active tier list there.