Two power sources for one MacBook Pro.

Mac will select the power supply with the most wattage:

Charge your 14-inch or 16-inch MacBook Pro - Apple Support

EthanW6258 wrote:

I have a 14" 2021 MacBook Pro. I currently use a thunderbolt hub which provides 86 W of power and services all of my peripherals, including a 4K monitor connected to a DP port on the hub. I would like to get a second monitor (5K 27"). All the monitors meeting the specifications I seek connect only by Thunderbolt/USB-C and all provide an (unnecessary) 90 W of power through the connecting cable. If I unplug my hub from its passthrough power source, it does not function.

Will I damage my MacBook if I plug the hub providing 86 W into one Thunderbolt port and the monitor providing 90W into the other.

I have read that the Macbook will select the port providing the most power and ignore the other, however, I have not seen this from an authoritative source (such as an Apple document). The experiment is obvious, but if my information is incorrect I've damaged a very expensive laptop which I depend on for my work. Has anybody done this or does anybody have a link to an authoritative source about this? Thanks for any help!

I do not know of an official Apple® Help Topic or Knowledge Base article to document or address your concern.

It has always been the macOS power management will select the most appropriate power source— without issue. The tag line "your Mac will never over charge" is repeated ad infinitum

You can always call Customer Support (800) MY–APPLE (800–692–7753)

or on line Apple Support

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple for support and service - Apple Support