When the Doxygen log contains global messages (without a filename or function name) following a local message (with a filename or a function name), then the global message is considered part of the local message.

Example:

/home/user/myproject/helper/SimpleTimer.h:19: Error: Unexpected character `"'
error: Could not read image `/home/user/myproject/html/struct_foo_graph.png' generated by dot!

The above is parsed as only one message, it should be two.