Well… personally I found my LJ deserving of emblems, because 1) it decently fixes the squishiness, his biggest weakness, to at least a passable level to face 5*, or tougher Titans, and 2) there is no 5* with just this special (I have no mana slowing 5* in my roster, only Leo who can steal some from 1 enemy). And it can even help the mana speed a little if you get that far down the talent tree (this won’t make him fast, but in combination with a mana troop it can make some difference).
Having said that, he is still not best used in all situations, but he can at times be really good especially paired with the right heroes. I do use him in war and for some raid attacks; also he can be quite good against certain bosses in events/quests or season 2 stages, and in a green stack against a blue Titan obviously.
None of this makes the case to keep the 2nd one though, which is what the question is… I would agree the sensible answer is to keep only 1, and yet I would hang on to the 2nd, space being relatively cheap… I did use a 2nd one in war for a time (at 3/60) when I had limited maxed 4*/5*, but not anymore now. And like @TheSchmoo said, there’s the off chance that you could get something useful out of him eventually in the Hero Academy, but that’s nothing but a gamble at this point.