The visa you currently have is irrelevant, it will be canceled and you will not be able to use it anymore once IRCC stamp your new visa in the passport and issue your CoPR. The expiry date of the new visa is usually 1 year from the date you took your medical exam (or till the expiry of your passport whichever earlier). So, if you will return before the expiry date of the new visa, you will be fine. In other words, forget about your current visas and wait to get the new visa stamp and check its expiry date before making any plans. Good Luck!