My mind just blew up. So you're saying either Woo Jin or Bum Gyun is dead, and needed to erase his memories and switch places in order to infiltrate the company? That doesn't make sense though...cuz if my twin brother was killed by illegal expirments, I would want to KEEP my memories, so my anger could fuel me to take down the company. Even if I did blame myself, for not being fast enough or whatever, I would still want to keep my memories, cuz at the end of the day it was the founders of SmartEarth that killed my brother and I would want to take them down, and achieve justice. 

Also Bum Gyun and Joon Hyuk (what you mean by future bum gyun right?) are really similar. Both can hide their emotions, both love chicken, both believe truth even if it sets them apart from their surroundings, both are determined, both have hinted relationship with Min Young, and the list could go on. I feel like Woo Jin is more similar to Ho Soo. Both will adapt to their surroundings and believe what they want to believe until a virtual slap in the face comes, both are determined, both are extremely loyal, both are naggers, both are determined, and the list could go on. I mean I can see some similarities between Joon Hyuk and Woo Jin, both play with their rubix cube all the time (but I think the 3 of them just do that always) and both have a similar story of trying to find the brother, and their intensity builds as the series goes on. And with Ho Soo and Woo Jin I can see some differences like Ho Soo is neater and can actually hide his emotions, but overall I feel like Ho Soo is the most similar to Woo Jin and Joon Hyuk the most similar to Bum Gyun.