Suppose someone advocates Theory A. He discovers that it is incompatible with some evidence, and is therefore falsified. So, he makes some changes, turning Theory A into Theory B. Is that cheating?
The answer is, scientists must be able to improve their theories. Otherwise, there would be no progress, and no learning. Also, by now we would be left with no theories at all. Both Evolution and Scientific Creationism would be long dead, with nothing to replace them.
However, if Theory A really is dead, then we have to stop using it. It would be sloppy (or dishonest) to explain some things with Theory A, and explain other things with Theory B.
Of course, if B is just A with a band-aid, then B may be unconvincing. There is an old joke that a camel is a horse designed by a committee. So one should ask: is theory B a horse, or a camel?