Hello from JustAnswer.
The fact that the patches are not synchronized does not really matter, as long as it is kept straight which patch was applied each day. Even in someone that will be on two patches indefinitely, it would be OK for the patches to not be synchronized. The patches essentially release a steady amount of the drug over 72 hours. There is a slight drop-off in blood levels towards the end of the 72 hours, but it is typically not enough to be clinically apparent and the patient does not notice any change in the effectiveness of the drug. If two patches are not synchronized, but each are left in place for the usual 72 hours, it will work the same. The difficulty is in not confusing which patch is due to be replaced on each day, and if the wrong patch is replaced, then it would make a significant difference.
In your case, since you are instructed to remove the patches once the morphine is given time to get into your system, the fact that the patches are not synchronized also will not matter, as long as both patches are still within the 72 hour window. When both patches are removed, then the drug will not longer be released, and the fact that one is 24 hours older than the second does not make a difference, since both are still within the period of steady release of the drug. Since it is less prone to error, we typically prefer to use two patches on the same schedule, but there is nothing intrinsically wrong with the patches not being synchronized.
If the second patch is due to be replaced before the morphine has time to get into your system, then you should still replace the patch on schedule, and then remove it at the designated time after the morphine is in your system. It may only be in place for 12 hour, but if you do not replace it, there will be a more significant lowering of the drug levels before the morphine is in your system.
If I can provide any clarification, please let me know.