I think ML in his "past" was injured and unable to talk so MC doesn't know his voice, he wouldn't know bruce is ML.
Actually he recognizes him the minute he sees him in that new reality but keeps doubting because he doesn't want to believe it, because ML used to be injured all over and because he didn't have any wavelength in the past.
This adaptation doesn't do a good job with this. In the novel, the Yoon from the past life was heavily scarred but it's not really drawn that way in the webcomic.
He already knows just by looking at his eyes alone
But he just being denial, probably because he cares too much, he hope the him in this world is just an ordinary man not just S class who wants to get revenge
If I remember correctly, he lost 1 of his leg and 1 of his arm right?
I think so but it’s been a while since i read the novel and i don’t remember exactly what injuries he had.
i think the least believable thing is that our super attentive wonwoo didn't immediately recognise yoon as bruce despite talking to him constantly for so long