I made a correction, as the Dual-port Full Duplex is for the SAS models only and are also SAS-specific features.
SATA is half-duplex, which means that data can only travel in one direction at a time and thus the bandwidth is shared between the input and output. SAS is full-duplex, which allows data to travel in both directions simultaneously, effectively doubling the bandwidth and reducing latency. This is important in a busy server where read and write operations often take place simultaneously.
The Dual-port feature, also specific to SAS drives, gives a redundant path when both ports are used. For example, each port could be connected to a separate controller, which means that if one controller fails, the other controller takes over to prevent downtime.