While completely duplicated files are rare, they are usually a sign of a simple oversight. Usually the required action is to remove all but one of them. A common exception to this rule may arise from generated code that simply occurs in several places in the source tree; the check can be adapted to exclude such results.

It is far more common to see duplication of many lines between two files, leaving just a few that are actually different. Consider such situations carefully. Are the differences deliberate or a result of an inconsistent update to one of the clones? If the latter, then treating the files as completely duplicate and eliminating one (while preserving any corrections or new features that may have been introduced) is the best course. If two files serve genuinely different purposes but almost all of their lines are the same, that can be a sign that there is a missing level of abstraction. Look for ways to share the functionality, by creating a new module for the common parts and importing that module into the original module.