Why two power ports on a budget laptop??

[dsimic]

I think more obvious answers could be;
* They thought 5v @3amp would be enough
* Pinebook Pro is their first USB-C charging device, so they wanted a backup plan for power in case it did not work well, (or at all), see above.

Unfortunately, the PBP's Type-C charging option doesn't seem to have been directed toward a backup plan.  According to the PBP circuitry, the maximum current allowed to be taken from the Type-C port is even lower than the maximum current allowed to be taken from the barrel connector.  More precisely, it's 2.52 A vs. 2.98 A, both at 5 V of course.