Nothing I hate more than seeing two files or more, sharing 90% of the same code. No matter what justification one attempts to use, there's a mistake somewhere i

Nothing I hate more than seeing two files or more, sharing 90% of the same code. No matter what justification one attempts to use, there's a mistake somewhere in the design / development process. I can see a case for what the OP is saying, but I feel it should always be seen as a temporary measure.