Is this a bug?

I've noticed that pikemen have some skill that lets them group up. When you fuse 2 pikemen with different bonuses you get one pikeman that has +1 str and all the bonuses of the previous 2, but when you split them, 1 gets no bonuses and the other gets all of them. With this method I made a pikeman that had all the bonuses that you can get at lvl 2, it was something like ~15-20 bonuses on a pikeman who has only 4 experience points and 11 str. I put him in a city and after few hordes he had almost every possible bonus and with 1 unit I was able to plunder 3 doviello cities, but couldn't take the capital cuz of the archer barrage. Even when a longbowman is protecting the city the pikeman has 99.9% chance to kill him. Just wondering if anyone has ever done this?

I've never actually tried that before. My games are usually over before pikemen get involved.