A failure in a check step is not the same thing as an error. A failure simply means that the check/test did not pass. An error should be reserved for unexpected exceptions, the application under test...
If you are using images to do the comparison you could have them log a warning instead of an error, or write out the number of times you see it. You can also use event handlers for the OnError event to suppress image check errors vs application errors. There is a lot of built in stuff that should be able to accomplish what you are trying to do.