So first thing that new players don't know that the final hand in Holdem is made up from 5 cards.

One person can have 2 pair like KK and QQ and the other can have AA and 22 and the person with the highest pair wins, in this case the guy with AA.

If they both have the same pair like KK then to determine the winner you look at the second pair, so for example if you both have KK and you have 22 but the other guy has 33 he wins the pot.

If you both have the same 2 pair, like KK QQ and if you both have KQ then of course you will chop the board because the kicker will be on the board.

If you have kicker in your hand, for example you hand is K9, the board is KQQ75 then you have 2 pair with a 9 kicker and if the other guy is holding a K then he has 2 pair as well, but you have an 9 kicker so unless he has a higher kicker than 9 he wins the pot, if he has the exact same hand as you K9 then you chop, but if he has something like K8 then you win because of your higher kicker that you were holding.

Could it be the case that in some hands you were holding for example K8 and the other guy had K7 and the board was KQQ92 then you both had 2 pair, but you both took the kicker from the board which would be 9, but you thought that your 8 would beat his 7?

I hope you understand what I wrote here