right now, the only AP we have that provides PSE on the second ethernet port is the AP-303P. In that case, if you supply the 303P with BT power, the power out will be AT. If you supply AT in, the 303P will supply AF out. If you supply AF in, no POE out will occur.
As Charlie mentions, the data sheets are the place to go, some of them with dual interfaces will do POE redundancy, and some model will do combining (AF + AF = AT or AT + AT = BT kind of thing).
You can generally connect a second AP to ENET1 of the dual-eth AP models to connect another AP, but if they are not the 303P, you will have to supply power to the second, daisy-chained AP via DC power or power injector). It's not recommended due to the daisy chain aspect, and if you use contorller based APs it can create issues with GRE tunnels if configured wrong (nested tunnels can create MTU issues that are hard to resolve).