First, a bit of an explanation about the reading of EKGs. Most modern EKG machines can provide a gross computer analysis of the reading; that analysis is not (or should not be) recognized by physicians as a valid interpretation of the test. It is also not recognized as the "professional" component of the test for reimbursement by any of the provincial health insurance plans. The only ones (in AB, BC and ON at least, but probably all others) who can interpret an EKG (and get paid for so doing) is a physician who is qualified in Internal Medicine (Cardiology is a sub-spec of IM) or a physician in another specialty who has completed additional training and certification in EKG interpretation. While many family docs may be able to do a gross reading of an EKG (though I know some who accept their limitations and refuse to even look at an uninterpretated strip), they are neither trained nor certified to do so beyond recognizing obvious abnormalities, nor are they usually able to maintain competency simply because they don't look at that many.
As has been reiterated time and again on this forum, this is not the place to come for a diagnosis based on a person's description of his problem and even an interpretation of test results is dodgy. The best that can happen is an explanation of the process and not the outcome.
It is highly unlikely that the specialist who read the second EKG will change his written interpretation. Probably two reasons there, firstly is that he probably feels his comments best reflected his analysis of the test (in other words, he thinks he is right) and secondly, this has now changed from an interpretation of a diagnostic procedure in order to provide knowledgeable medical care to a patient to being part of a non-medically necessary process, i.e. getting hired by an employer. The $15 (or probably not much more) that he was paid for his work doesn't cover that.
What does this mean to rcampbell and his next steps to overturn the decision of the RMO (who is in Borden not Ottawa, unless they have changed his location)? If I understand correctly, his "letter of doom" simply stated that he did not meet enrolment standards because of the long QT; it was not an invitation to submit additional medical tests or opinions in order to clarify the circumstances and potential outcome of the condition. Therefore, rcampbell probably has only two courses open to him if he still hopes to join the CF (edited to add this after ModlrMike's following post about reality). He can submit the second EKG with a request that his situation be re-examined by the RMO; it may be helpful if the second EKG is accompanied by a report from his family doctor explaining the situation and containing his opinion that there is nothing wrong. However, based on rcampbell's explanation of what his GP has done to definitively rule out LQTS, there may not be a lot of meat in such a report, even if his doctor would so state. (Of course, my analysis of this may be wrong.) His second option would be to have a diagnosis of LQTS definitively ruled out by a specialist which at the same time could provide an explanation for the long QT noted in previous EKGs. If that was to happen, he could then submit that greater evidence for review by the RMO.