Doubled pawns leads to a weak game for the player who has them. Doubled pawns can is defined as having two pawns directly in front of one another. This is the result of an earlier capture. What is worse is that these doubled pawns often become isolated pawns. Isolated pawns are unable to be guarded or defended by another pawn. If you have two pawns in the same vertical file without an ability to guard them with each other, then you have a major weakness that will most likely haunt you later in the game.
These doubled and isolated pawns are just waiting to be picked off by your opponent. You opponent may elect though to simply ignore them since they are of very little threat unless they reach the back rank and get promoted to queens. This is easily avoided by blocking their path with a pawn of your own. The other disadvantage of having doubled your pawns in the game of chess is that you have also opened a file that your opponent can use to mount an attack onto your back row.
The best thing that you can do is to try and avoid doubling up your pawns in this manner. In order to avoid this mistake you must utilize careful planning from the beginning of the game. Using other primary pieces to be able to capture attackers that your opponent sends out will help you avoid the double pawn weakness. At times it may be unavoidable to double up your pawns, but being aware of the disadvantage it presents and being able to recognize this will help you in your game. Also you should know that you could exploit this double pawn mistake in your opponent and that if your opponent makes this error that you are at an advantage.