Schneier's summary of Wheeler's method says: "This countermeasure will only fail if both [compilers] are infected in exactly the same way. The second compiler can be malicious; it just has to be malicious in some different way: i.e., it can't have the same triggers and payloads of the first. You can greatly increase the odds that the triggers/payloads are not identical by increasing diversity: using a compiler from a different era, on a different platform, without a common heritage, transforming the code, etc."
