This myth is FALSE.
All courses taken full time at the undergraduate level in the September – April academic sessions will be considered toward your GPA. Typically, if you have more than one undergraduate degree, they are both considered equally.
However, if you have taken two degrees and there is a significant difference between the GPA in each, you can submit an Academic Explanations Essay as part of your OMSAS application highlighting the circumstances around this. Every situation is assessed on a case-by-case basis, and may be subject to further verification.