Keep more than 1 heroe

I’ve been on for 3 seasons and at first thought it was good to level up duplicate heroes. With all the added new heroes, I wonder if it’s still a good idea? I know many ask what the line up is. I play a lot, but would not consider myself to be “an avid” player, just mostly for fun, but do enjoy trying a new theory now & again to get better results. Thanks for any comments.

More context is needed, but generally

Dupes can be good in wars. For example I have four costumed emblemed Rigard , 3 x 18 and 1 x 15. Very handy to have a booster cleanser at nine tiles in every team if you can

Multiples of Proteus and BT also.

As materials to raise up 4* heroes are bountiful for me now, 4* star dupes are a fine idea

There are not many fives I would do a second one of due to scarcity of mats. Like I would probably do a second GM, of course I’d need a first GM before that though

Duplicates of particular heroes can be worth levelling up. Healers are quite scarce among 5* ranks so having multiples of the 4 star ones is useful. I have 3 Melendors and 2 Rigards and they are handy for wars and events like Ninjas and the Tavern where there are restrictions on the number of heroes.

As stated, it depends on the hero. Some are definitely worth keeping duplicates, some are barely worth keeping one. I have been playing for almost three years as mostly f2p and have yet to max some 5*'s like Quintus, Obakan, Elkanan – but I do have maxed dupes of Sartana, Lianna, and Joon. In 4* I have maxed dupes of the healers, dispelers, and pulverizers.

Of course for me the question of maxing a dupe non-S1 hero that isn’t a 3* is moot.