Apple Magsafe charger

I recently bought an Apple Magsafe charger for my iPhone 12. Do any of you have experiences wherein the Magsafe charger has to be plugged in alone? Because I also bought an Aukey dual-port USB-C wall charger. And plan to use that for charging my phone and my watch, but when I plug them both it seems that only my watch is charging and not my phone (charging through Magsafe). So the Magsafe doesn't work with dual-port wall chargers or it doesn't want the power to be shared. Is this true?